Reach, vigilance
Whenever Finneas attacks, put a +1/+1 counter on each other creature you control that's a token or a Rabbit. Then if creatures you control have total power 10 or greater, draw a card.
Players can't take actions in between the time you put counters on creatures with Finneas's last ability and the point at which that ability checks the total power of creatures you control. Notably, they can't try to reduce the total power of creatures you control by removing them from the battlefield or reducing their power directly.