Savageborn Hydra

Battalion — Whenever this creature and at least two other creatures attack, this creature gains lifelink until end of turn. (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Regenerate target creature.

Whenever this creature attacks, you may pay W. If you do, tap target creature an opponent controls.

Detain up to two target creatures your opponents control. (Until your next turn, those creatures can't attack or block and their activated abilities can't be activated.)

Vigilance Multicolored creatures you control have vigilance.

Each player sacrifices a multicolored permanent of their choice.

You gain 1 life for each creature your opponents control. Prevent all damage that would be dealt to you this turn.

When this creature enters, if you cast it from your hand, create a 1/1 white Bird creature token with flying, then populate. (Create a token that's a copy of a creature token you control.)