Selaya, Nurturer of Broods

First Strike, Lifelink, Evolve

If you would spend mana on an X cost, you may add {1} for each Hydra you control. This mana can only be used to pay for X. Whenever you cast a spell with X in its mana cost, draw a card if its X value is 4 or greater.

Whenever a nontoken Hydra enters the battlefield under your control, you may populate. (Create a token that’s a copy of a creature token you control.)