Grist, the Ever-Swarm

Flying
At the beginning of your upkeep, mill a card.
If you mill a creature card this way, you gain
1 life and create a 1/1 black Insect creature token.
{b}, Sacrifice an Insect: Target creature gets
-1/-1 until end of turn. If that creature dies this turn, put a +1/+1 counter on Grist, the Ever-Swarm.