Cartouche of Strength

Enchant creature you control
When Cartouche of Strength enters the battlefield, you may have enchanted creature fight target creature an opponent controls. (Each deals damage equal to its power to the other.)
Enchanted creature gets +1/+1 and has trample.

Gaea's Embrace

Enchant creature
Enchanted creature gets +3/+3 and has trample.
{G}: Regenerate enchanted creature.

Tuya Bearclaw

Whenever Tuya Bearclaw attacks, it gets +X/+X until end of turn, where X is the greatest power among other creatures you control.