Xurkitree

{0}: Put a Volt counter on Xurkitree. This ability
costs {1} more for each Volt counter on Xurkitree.
{t}, Remove X Volt counters from Xurkitree: Xurkitree deals twice X damage divided as you
choose among any number of targets.
It apparently acts like a tree in its home world, sucking
in electricity from the ground when it's low on energy.