Sycamore the Wise

Convoke
All creatures on your opponent's side of the battlefield gain Decay. Whenever your opponent summons a creature, give it Decay.
Sycamore is a Life Tree, one that has lived for
countless centuries. He is very good at keeping the
forest not only safe, but also stable. Aside from that,
he is very good at taking care of intruders. Expansion's
never been on his mind, though.