Tac Nayn, Voice of Selesnya

Flying, Trample
Convoke
Tac Nayn, Voice of Selesnya's power and
toughness is equal to twice the number of
creatures tapped for convoke. You may tap
opponents' creatures for convoke. All creatures
tapped for convoke gain +X/+X or -X/-X, where
X is the number of creatures tapped for convoke.