Udbarg, Fist of the Gruul

Partner with Kjaten, Clan Patriarch
When Udbarg attacks, you may tap any number
of other untapped creatures you control. Put a
+1/+1 counter on Udbarg for each creature that
you tap this way.
If Udbarg's power is 6 or greater, it has trample. If
its power is 12 or greater, it has double strike.