Re: (Nutaku) Milenium War Aigis (English Version)
Now use it to level units past CC40. Immortal Beast is, in my eyes, a stepping stone - when you are able to farm it, it opens way for reliable high-leveling of units. High money income combined with a good drop of fat feeders. Dragon Hunting is sort of comparable, but way slower - an alternative for when you just can't stomach these 30 min of farming and have to do it on afk-map.
Way I do it for Platinum units is: RtR up to level 40, then switch to IB, go up to 62, use 2x cans. For Black I stop using Iron feeders at 62-64 and switch to combination of 3 Roy feeders + trash (Gold or, if there's too much of them, Plat) fairy while using the rest to level other units. ~740 exp per round is relatively good and does not hit the wallet much. This way, my Karma is steadily growing and is at 68 ATM - going for 70 or 74 to hit 2-3 tin can range.