Last edited by Ramazan; 02-21-2016 at 08:48 AM.
Immortal Beast's big advantages are the Prince experience gained and the cost savings you accrue over time by using level 20 fodder instead of lower level units. The map really only sacrifices the rate at which you gain unit experience and while that's not insignificant most players find it quite manageable given that beating Immortal Beast requires a fairly mature team in the first place. It's a great map for putting your team on cruise control and slowly creeping your CC'd units towards level 50+ without breaking the bank.
for story missions, which map should i grind to get unit for leveling up?
edit: beside immortal beast
flame dragon also gives good unit xp.
Flame Dragon and Dragon Hunting. Although that depends on if you reached those already.
You can take a look at the charts here and mix'n'match
http://millenniumwaraigis.wikia.com/wiki/Story_Missions
actually drop rate is random and you can get unlucky, but dragon hunting only drops 3 iron and 1 bronze at max, while most other maps drop 4 irons and 1 bronze at max, which is why some people don't like dragon hunting. however, DH lets you save gold (due to less unit drops, so less gold used since you combine less often), while flame dragon and remnant vanquish both has fairly decent unit exp, gold and prince exp rates.
Aigis misc. resources: http://harem-battle.club/dmm-version...html#post49732
Beginner Guide for choosing units to level: http://harem-battle.club/millennium-...ling-team.html
Past DMM Aigis data for personal archiving: http://harem-battle.club/dmm-version...html#post33260
FKG Raid Bosses: http://harem-battle.club/flower-knig...id-bosses.html