Grenzo, Dungeon Mentor

Grenzo, Dungeon Mentor enters the battlefield
with X +1/+1 counters on it.
{2}: Put the bottom card of your library into your graveyard. If it’s a creature card with power less
than or equal to Grenzo’s power, put it onto the battlefield.
Whenever a creature enters the battlefield,
if it's power is 2 or less you may pay {1}.
If you do, draw a card.