When Pridemalkin enters the battlefield, put a +1/+1 counter on target creature you control.
Each creature you control with a +1/+1 counter on it has trample. (They can deal excess combat damage to the player or planeswalker they're attacking.)
Pridemalkin can be the target of its own first ability.
Pridemalkin's second ability applies to Pridemalkin as long as it has a +1/+1 counter on it.