Felothar, Dawn of the Abzan

Trample
Whenever Felothar enters or attacks, you may sacrifice a nonland permanent. When you do, put a +1/+1 counter on each creature you control.

Ouroboroid

At the beginning of combat on your turn, put X +1/+1 counters on each creature you control, where X is this creature's power.

Whenever another Human you control enters, put a +1/+1 counter on Kyler.
Other Humans you control get +1/+1 for each counter on Kyler.