[Gatts]

They may be extreme usefull in not few battles - true. But bein overpowered, they have to be usefull all the game - what is not true - later on nearly none of their abilities is usefull:

low leadership? (20) -> more you have - more you loose (vulnerable, low HP)

no retaliation? -> not such a big deal - if they can't kill their target on first hit ... still it is handy, but not powerful

Lulaby? -> how many units are later on lulable? really... not many as far as I know

summon thorns? -> yep - they can take some damage - but later on it is no big deal for enemy to sway away thorns like nothing (as later on are used area efect spells, abilities and mostly fire based)

Is fast? -> well, it give a clear bonus for tactics, but well, you need only one fast unit in army to get first cast and rage use. Other fast units just wait and hope not to be targeted by enemy spells/ archers

Increases speed of elven units? - This could be real handy - for hunters/ elves who by this spell may go first even second round (when you first round +INIT does not apply anymore) so this could get handy... but again, not powerful

Dryads provide very large variety of tactics and combinations, which may look cheating-like, still I voted that they are not overpowered.