Ahriman
Tyrant
but it would be nice if i could cast mutation on another unit than the warlock and the units in the same tile... cause that one doesent pick a random enemy =( you COULD use the unitmissile method: a targeted spell summons a unit, this unit then moves onto whatever the target is and BAM! the effect is applied to the target. Thats how the firaball spell worked in Fall From Heaven: Age of Ice.
There are many spells that work like Fireball, but that wouldn't really make sense for non-combat buff spells like mutate. Mutate only works on your own troops, not on enemy troops.
The AI can cast mutate to affect all the units in its own stack - all enchantment spells work this way - but how would you get it to understand summoning a "mutation spell" unit that it was supposed to then move into another tile?
If you want it to target particular units of yours, just micro them to move into the stack with the warlock and then cast the spell.
I see no possible gain for trying to make this a targeted spell.
The only spells that could use targetting are things like dominate and charm person and pillar of fire type spells, but these auto-target the largest enemy stack in range, which works fine.