Nathanial, Malicious Ward

Nathanial enters the battlefield under the control
of an opponent of your choice.
At the beginning of your end step, put a
+1/+1 counter on Nathaniel. Then draw a card
and create a Treasure token. Nathaniel's owner
does the same.
{b/r}: Put a -1/-1 counter on Nathaniel and goad it.
Nathaniel deals damage equal to its power to its controller.
Only Nathaniel's owner may activate this
ability.