Arjax, Caller of the Pride

{4}{w}{g}: Monstrosity 3.
Whenever Arjax, Caller of the Pride becomes monstrous, Arjax, Caller of the Pride gains lifelink and trample as long as he's on the battlefield. This spell can't be countered.
Whenever you gain life, put a +1/+1 counter on Arjax, Caller of the Pride and put a 2/2 Cat Warrior creature token with lifelink onto the battlefield.