Just to inject some facts into the discussion:
- Animate now requires concentration. It appears on the release list and you can use it to dismiss your animates prematurely if you wish. The current concentration is not even half of a detect magic spell.
- Most casters can animate 25-30 undead if they really want to go to the max. However, I hope and assume that people will want to keep concentration free for their other spells, so 12 would be a more reasonable amount for daily use under the current settings.
- Animate does not cause mana drain. It costs the same amount to animate an undead as before. Undead last the same amount of time as before.
- The concentration cost for control undead has been cut in half. If you are concerned your animate tank doesn't last long enough, you might want to try checking out using a controlled undead instead.
This is all part of tuning. We'll see if it needs changes or more adjustment as things go forward.
This change that took place last year was to put a cap on massing undead by the way of having concentration on them. Has it really done the job? Necromancers still wander around with a ton of undead whether by self-creation or magical devices.
Further more, as the poster Sypher has already covered, some necromancers forsake spell-casting completely by creating a ton of undead and then zap the etherealform wand non-stop, staying etherealform whenever melee risks arise.
Limiting the number of undead to that of a group may be too few, because not all different animated dead come in same strength. Perhaps the more powerful versions could use more concentration than their weaker counterparts.