Pehajek

Flying, trample, haste
Pehajek enters the battlefield with four +1/+1 counters on it.
At the beginning of each upkeep, put a +1/+1 counter on Pehajek.
If Pehajek has seven or more +1/+1 counters on it, it gains first strike and instead of gaining 1 +1/+1 counter each upkeep, it gains 2 +1/+1 counters.
If Pehajek has sixteen or more +1/+1 counters on it, it gains menace.