Yisix, Battle Bound Crocodile

Trample, rampage 2 (Whenever this creature
becomes blocked, it gets +2/+2 until end of turn for
each creature blocking it beyond the first.)

Whenever Yisix, Battle Bound Crocodile
becomes blocked, put a +1/+1 counter on Yisix
at the end of combat.
As long as Yisix has five or more +1/+1 counters
on him, he has doublestrike.