Herjafan, Glacial Destructor

Herjafan, Glacial Destructor enters the battlefield
with three stun counters on it. When Herjafan,
Glacial Destructor enters the battlefield, tap it.
When Herjafan, Glacial Destructor attacks, tap
all nonland permanents defending player controls
and put a stun counter on them.
{2}: Exile Herjafan, Glacial Destructor. Return it
to the battlefield at the beginning of the
next end step.