Whenever Defthand Infiltrator deals combat damage to a player, put a +1/+1 counter on it if it doesn't have one on it.
Defthand Infiltrator can't be blocked as long as it has a counter on it.

When Gnosa, Research Executive enters, gain control of target nonland permanent until the end of your next turn. Untap it.
Each creature you control but don't own must be blocked if able and must be the target of spells its owner casts if able.