General strategy: Raids are the economic lifeline. To increase the chances for items and more cash, better quality units need to be dispatched. In every case, a level 1 unit from a higher tier is worth more in raid calculations than a level 3 unit of the lower tier.
Goblin > Roper > Slime = Imp > Ogre = Lich > Gazer > Demon
Battles: Higher difficulties mean more enemies at higher levels. So if players survive with minimal casualties, that's more red souls to play with. The hard part is minimising the casualties, especially early on when there's nothing much to work with and even villagers can kill goblins. As the game progresses, the invaders come in increasing quantities and with higher quality troops, some of which require specific units at certain levels to counter.
Tech tree: Left to right, top to bottom.
調教1 + 2: Required to train Rayna. Girls from Clare onwards need level 2.
乙女の肢体: Unlocks nude sprite.
レベル上限解放(ヘロイン): Requires 調教1. Increases heroine level cap to 4 and 5 respectively. The last upgrade allows more sex scenes at request starting at 100 red souls, increasing by 100 for subsequent applications. Stat increase is quite minimal (+1-2 for attack and defence and a small HP boost) but is worthwhile if some heroines are not cutting it at later chapters.
レベル上限解放(魔族): Increases monster level cap to 4 and 5 respectively.
リサイクル: Dead friendly units refund spent red souls by 20%, 45% and 75% respectively. Pointless in Easy, very useful from nightmare onwards because of the casualties involved and the need for red souls regardless of where players are in the game. Early on, players won't have the funds to invest in red soul cap and captive overflow is very likely. Might as well use the red souls productively.
With this researched, players with maxed out rosters will want to get the levelled obsolete minions killed off instead of dismissed to reclaim some of the soul to investment.
防衛魔法: The spells used during the battle phase.
アーケインビーム: Magic beam from the sky which damages a random enemy unit. Use it when available, only worth holding if there's a chance it will kill an almost dead unit instead of one which is on full health (or players were slow in reacting).
カースタッチ: Random enemy unit is temporarily afflicted by status debuff. Possible candidates include blind, confusion, slow, amnesia (cannot use skills except basic attack) and poison. Use whenever it's available, it really shows its worth when it's just the enemy heroine remaining.
テレポート: All enemy units are teleported from their current position to a random area of the dungeon. This could be anywhere, even the same room but a slightly different position. Can't spam this like the other two, mostly used when a unit is nearly dead and players want to try to save the unit by letting something else in the dungeon handle the intruder. Increasingly effective towards the end of an invasion.
テラーボイス: Units are temporarily stunned and cannot take any actions. Timing for this one is tricky; it is best used when there are multiple enemy units engaged in battle with friendly forces. Getting the timing right means they will be sitting ducks which will keep casualties down if friendly units can dispatch them quickly before the effect wears off. Not a spell to be used lightly, using it early sees the spell used at most 2-3 times a battle.
アーケインブラスト: Magic circles deploy in every dungeon room. After a few seconds, they explode doing massive damage to all enemy units inside the room. Doesn't affect enemies in corridors. Tricky to get this right because of the delayed action and the effect is maximised when all enemy units have been deployed. Try using it early, preferably when a large group of tough enemies enters one room. That way the damage is guaranteed as they're fighting and there might be another opportunity later in battle to use it again.
闇商人: The merchant. Without this researched he won't show up at all. Extremely useful regardless of when he shows up since he allows buying and selling of resources. Only one of each trap or creature resource can be bought per visit. Great for disposing of excess sacrifices in lower difficulties in exchange for cash.
お得意様1 + 2: 15% discount on purchases and 20% increased chance of visit respectively.
Units:
Goblin
HP 84, ATK 22, DEF 20
HP 92, ATK 24, DEF 22
HP 101, ATK 26, DEF 24 Dual Strike
HP 110, ATK 29, DEF 26
HP 118, ATK 31, DEF 28 Critical Attack (15% chance for regular attack to deal +50% damage)
Cannon fodder. Best used to reduce excess sacrifice headcount early on. Only thing going for the very early stages of the game, but not worth improving to level 3 because dual strike is an active ability with a cooldown interval.
Roper
HP 100, ATK 22, DEF 22 Armour break (Enemy defence decreased by 20 for 7s)
HP 110, ATK 24, DEF 24
HP 120, ATK 26, DEF 26 Weapon break (Enemy attack decreased by 20 for 7s)
HP 130, ATK 29, DEF 29
HP 140, ATK 31, DEF 31 Critical Attack
Upgrade raiders to this unit as soon as possible. An overall improvement over the goblin and the stat debuffs are surprisingly useful against heroines like Mavis when AOE attackers are in the same room. When raiders guarantee 100% chance of mana potions each turn, this is the unit to turn to for excess captive consumption because it only uses one captive.
Slime
HP 150, ATK 21, DEF 28 Protection (Buff defence by 20 for 7s)
HP 172, ATK 23, DEF 32
HP 195, ATK 24, DEF 35 物理耐性 (Physical damage reduced by 30%)
HP 218, ATK 26, DEF 38
HP 240, ATK 28, DEF 42 再生 (HP regenerates by 10 every 5s)
Weaker attack than its lower tier counterparts in exchange for surprising durability, especially at level 5. Nightmare and above will be a decision on how to balance the number of slimes available for dungeon deployment when imps are still not available. Despite the strong defence, they are more vulnerable to magic attacks and HP regeneration isn't much help if they're overwhelmed.
Imp
HP 110, ATK 33, DEF 20 (Magic), Explosion (deals magic damage to one enemy)
HP 120, ATK 37, DEF 22
HP 130, ATK 42, DEF 24 Spark (Magic damage to one enemy, 40% chance to inflict blind)
HP 140, ATK 46, DEF 26
HP 150, ATK 50, DEF 28 Firestorm (Magic damage to all enemies in room)
Glass cannon, but it's the first unit with a magic attack. Against units with high physical defences, this is the unit to turn to. Advise deploying at least one in Rayna's room because of its special abilities until upgrades are available.
Ogre
HP 200, ATK 28, DEF 30 Dual Strike
HP 238, ATK 32, DEF 34
HP 275, ATK 35, DEF 38 物理耐性
HP 312, ATK 38, DEF 41 魔法耐性 (Magic damage reduced by 30%)
HP 350, ATK 42, DEF 45 Earthquake (Physical damage to all enemies in room, 30% chance to inflict stun)
Upgrade over the slime, it trades the ability to regenerate at level 5 for improved physical damage and resistance to both magical and physical attacks. The most durable unit in the game despite the 45 DEF; deploy this with some way to heal units and they'll remain useful until the end of the game.
Lich
HP 140, ATK 40, DEF 22 (Magic), Cold snap (Magic damage to one enemy, 40% chance to inflict slow)
HP 152, ATK 45, DEF 24
HP 165, ATK 50, DEF 25 Spark
HP 178, ATK 55, DEF 26 Firestorm
HP 190, ATK 60, DEF 28 Blizzard (1.01 fix: Magic damage to all enemies in room, 40% chance to inflict slow.)
Highest damage from minions in the roster. Only 40HP improvement from the imp at level 5, so clever deployment is required to keep it alive. Not suitable for prolonged engagements because of its poor HP and DEF, but for battles which require a quick kill and/or fighting almost dead opponents this unit is more than capable of fulfilling its role. Best used for raiding when it's available, swap out when Gazers are available.
Gazer
HP 140, ATK 26, DEF 26 Mind Blast (Magic damage to one enemy, 75% chance to inflict amnesia)
HP 182, ATK 31, DEF 31
HP 225, ATK 36, DEF 36 Mind Hack (Magic damage to one enemy, 50% chance to inflict charm)
HP 268, ATK 42, DEF 42 Reveal (Passive ability, hidden enemies have a 75% chance of revealing themselves when the room is entered)
HP 310, ATK 47, DEF 47 Area charm (50% chance to charm all enemies in room)
Prime example of a unit which must be upgraded before it can be deployed. Less useful than the lich at level 1, it has to be level 3 minimum to deploy in dungeon. This is the only non-heroine unit with reveal, so deploying them closer to Rayna's room should stop assassins from making it all the way unseen. Charm makes an enemy unit fight for the player for the duration of the effect. Enemy units will engage other hostiles in the same room; if there are no enemies in a room the charmed unit will wander off in a random direction until the effect wears off. For trap heavy dungeons, it's not a bad idea to deploy gazers at the front lines as there's the chance an invader gets sent back to a trap filled room if it has no hostiles to fight.
Demon
HP 270, ATK 32, DEF 32 Cyclone (Physical damage to all enemies in room)
HP 292, ATK 36, DEF 36
HP 315, ATK 41, DEF 41 Firestorm
HP 338, ATK 46, DEF 46 Blizzard
HP 360, ATK 50, DEF 50 Earthquake
The all-round unit. Useful even at level 1 because of the AOE cyclone. Because of how expensive and rare it is, might be better off using it to fill raider slots since the lower tier units can do a good enough job with trap help. Always buy the resource from the merchant when it's available, but care should be taken with deployed demon units to ensure the investment isn't wasted.
Traps:
毒の術式: Poison trap. Enemies entering the trap will be poisoned for a short period. Poisoning removes a % of their total health, so higher tier enemies lose more per interval than villagers. The only trap guaranteed to do damage, so it's useful throughout the game. Best placed at the dungeon entrance as a welcome mat. Poison isn't lethal, but spells can finish the job against stricken enemies.
鈍化の術式: Slow trap. Enemies entering the trap are slowed down. In addition to the decrease in movement speed, they attack slower when in combat (from observation they attack once for every friendly unit's two). The other trap in the roster with a guaranteed effect, this one is best used in conjunction with other traps because it deals no direct damage on its own.
稲妻の術式: Lightning trap. At set intervals, the trap will deal lightning damage to all enemy units within the room boundaries on activation. More damage than the poison trap, but the timing condition means players will more than likely find this trap useless. Best used in conjunction with the slow trap since enemies who enter the room take longer to leave, allowing the trap to do its work. +50% damage to enemies afflicted with confusion.
幻惑の術式: Confusion trap. Enemies entering the room have a 50% chance to be confused. Confusion makes an enemy stop what it's currently doing and wander aimlessly around the dungeon until the effect wears off. Unlike the spell, the trap's effect lasts longer. Combo with the lightning trap for more damage. Unfortunately the 50% effect means this trap will whiff, which limits its effectiveness. If it does work, waves will be drawn out allowing players more time to kill the stray enemies with spells.
隕石の術式: Meteor trap. 75% chance to drop a meteor which will damage all enemies in a room each time an enemy enters. This is the main damage dealer; the 75% chance triggers often enough that a group of enemies pass through risk multiple bombardments. As an added bonus, slow enemies take 50% more damage. The base damage is roughly equivalent to the lightning trap, but the trigger mechanism is probably more reliable because of the sheer number of invaders on higher difficulties.
次元の術式: Dimensional trap. 35% chance to teleport enemies who enter back to the dungeon entrance. A typical staple of tower defence games, players who are reliant on traps rather than minions will probably use this. I don't like the trigger chance, so not worthwhile unless players are desperate and are swimming in cash for some reason.
The trap is best used when there are three rows available between entrance and the first line of defence. Having a row of these backed up by traps on the first two rows is feasible, especially on Nightmare chapter 6 and most of Hell difficulty.
高揚の術式: Euphoria trap. Enemies who enter this room will trigger a stat buff for a random friendly unit in an adjacent room. The buff is +12 to ATK and DEF for 50 seconds. I didn't try this out, but if the effect stacks this can be lethal for invading waves, especially if the room has mages/heroines with AOE attacks. The buff lasts long enough for friendly units to dispatch multiple enemies while the effect lasts. Unfortunately the resources and costs of this trap are very high, so it's not practical to use this en masse.
吸収の術式: Absorption trap. At set intervals, the trap will drain the life out of enemies and heal all friendly units by a small amount. 50% more damage if enemy is poisoned (with slightly better life restoration for friendly units). The damage is surprisingly potent even without poison, while the life heal is a small but useful bonus to increase the survival chances of friendly units. The trap resource is very rare and the mechanics are the same as the lightning trap, so utility is maximised if a lot of slow-moving enemies have to pass through this at higher difficulties.
金庫の拡張1-3: Increases treasury cap by 500, 800 and 1200 respectively. Get this in good time before the research costs start spiralling beyond the treasury cap.
牢屋の増築1-3: Increases sacrificial victim cap by 2, 3 and 7 respectively. Get ASAP, more prisoners to work with is a good thing.
秘薬研究1-3: Red soul cap increases by 150, 500 and 2200 respectively. Almost always top of the list for investment, players will need to time this so that it minimises red soul overflow.
Row of heroine icons: Don't have to do anything about this since entries are unlocked as the story progresses. Players can invest gold to shorten the research time (which I don't recommend except for the final icon).
兵舎の増築1-3: Unit increased by 4, 6 and 10 respectively. Heroines do not count. By the end of the game players should control a maximum of 45 units.
部隊の管理1-3: Raider cap increased by 2,2 and 3 respectively. Research ASAP. More raiders means more resources bar red souls. How quickly players research this will be crucial at Nightmare and up.
Heroines:
Rayna
Level 1: Area Protection (Everyone in room +20 DEF for 7 seconds)
Level 2: 混沌の抱擁 (All allies in dungeon +10 DEF for 15 seconds)
Level 3: 混沌の祝福 (All allies in dungeon +10 ATK for 15 seconds)
Level 5: 混沌の救済 (Passive, if she receives fatal damage she heals 25% of her total HP and all enemies in room are teleported back to the dungeon entrance. Only triggers once per battle).
Main heroine and last line of defence. If she dies, it's game over. Highest HP pool of all, but the second worst combat stats amongst the heroines. All of her special abilities are support. It's recommended to upgrade her to level 3 ASAP for the dungeon wide boost. Level 5 comes in handy at higher difficulties when assassins make it through, otherwise it's a last throw of the dice in hopes the room enchantments in front can finish the job.
Claire
Level 1: First aid (Recovers HP)
Level 2: Beginner's luck (10% chance damage from normal and special attacks is increased by 100%)
Level 3: Dual strike (Two consecutive physical attacks against target)
Level 5: Learning (Uses a random attack skill in allies' skillset)
The rookie heroine is the worst fighter of all, but she's crucial early on when dungeon minions aren't cutting it against the new invaders. Her ability to heal gives her a semblance of durability, but it is not reliable enough to keep her alive in prolonged engagements. Learning depends heavily on the allies she occupies the room with, my personal preference is to let a Lich/Demon and a Gazer stay with her (the Demon and Lich have all of the AOE attack abilities, while the Gazer has crowd control).
Mavis
Level 1: Dual strike
Level 2: Braveheart (Passive, DEF increases as her HP depletes.)
Level 4: 物理耐性
Level 5: Cyclone
The warrior is best suited for typing up enemies so that the player can blast them to death with spells. Arguably the most durable heroine against physical attacks because of her passive and the level 4 skill. She's ok on the offensive front once she learns cyclone, but otherwise has to rely on (slowly) hacking enemies to pieces.
Jessica
Level 1: Area heal (All units in room are healed a fixed amount of HP)
Level 2: Area Protection
Level 3: Area Force (All units in room +20 ATK for 7 seconds)
Level 5: 範囲拡大 (Passive, 50% chance her skills will extend to friendly units in adjacent rooms. Adjacent rooms referring to those which are connected to Jessica's room)
Invaluable for her healing and support skills. She's a slightly better fighter than Claire and will not last long if she's engaged in combat for too long. Her skills stack with Rayna's; the difference between buffed and unbuffed units in combat is quite obvious. Her range extension also applies to the heal spell, however this paradoxically relies on her being placed in a position which will both attract enemy attention (the centre) and impact as many rooms as possible. She won't use the heal spell if she and her room allies are unharmed, so it's not a reliable method to provide healing for multiple rooms.
Melwen
Level 1: Dual strike
Level 2: 魔法耐性
Level 3: Reveal (75% chance stealthed enemies will break cover when entering the room, forcing them to fight)
Level 5: Area Charm
Decent combat stats, Melwen's utility is in crowd control and as a counter to assassins. Once she's at level 5, she basically plays like a Gazer with physical attacks. 75% chance is usually enough to stop assassins in their tracks, so it's not necessary to deploy a Gazer in the same room as she is. Her skill set in Hell difficulty is very different from her dark elf version.
Rin
Level 1: Spark
Level 2: Cold Snap
Level 4: Firestorm
Level 5: Blizzard
The Lich in human form. Comfortably the highest attack of all the heroines, but if she's hit she'll fall quickly because of her abysmal HP and DEF. Upgrading doesn't really help her HP and DEF numbers, so players intending to use her will want her on the same row as Rayna.
Asuka
Level 1: 心眼 (Same as reveal, but with a Japanese skill name)
Level 2: 疾風陣 (All allies in room are hasted. Hasted units have at least 2 attacks to an enemy's one).
Level 4: 空蝉 (Passive, 25% chance to avoid enemy attack)
Level 5: 首狩り (Passive, 3% chance to instantly kill enemy unit. Skill does not work on heroines)
Another heroine with slightly changed skills after she's converted. Extremely capable attacker and all units in her room will slaughter enemies much faster than their peers. Her DEF and HP are below average because she relies heavily on her passive ability to avoid damage. Definitely put her on the front lines, together with a Demon and an Ogre to rack up the kills.
Mizuho
Level 1: 一閃刃 (Physical attack which also lowers enemy DEF)
Level 2: 逆境 (ATK increases as her HP depletes)
Level 4: 明鏡止水 (Passive, 60% chance she will remain alive with 1 HP when she receives fatal damage)
Level 5: 絢爛舞刀 (AOE Physical attack which lowers enemy DEF)
Lower attack than her compatriot, but superior HP and DEF. Her attack increases in potency as she takes damage, her passive ability allows her to keep fighting at maximum ATK for longer. Even without her attack boost, she's definitely capable of finishing enemies off on her own without requiring long duels. She'll still fall if forced to fight extended battles, so not a good idea to place her in the centre.
Henrietta
Level 1: 守護のオーラ (All allies in room increase DEF by 15 for 12 seconds)
Level 2: 裁きのオーラ (All enemies in room take magical damage)
Level 3: 衰弱のオーラ (All enemies in room decrease ATK by 15 for 12 seconds)
Level 4: 苦悶のオーラ (All enemies in room are inflicted by Poison, Slow, Blindness or Amnesia. Only one debuff per aura, chosen randomly)
The strongest heroine overall. Same skill set as the Paladins; her auras work like a lightning trap and trigger at set intervals automatically unlike active skills. Her overall combat potential thanks to her abilities is better than anyone else, so park her in the centre to take the brunt of invaders. Good results when paired with a Demon and a Gazer who benefit from the stat buffs and debuffs.
