Brain of Mensis

Frenzy-At the start of each upkeep, each
creature or planeswalker under that player's
control gains one frenzy counter.
Once a creature has 3 frenzy counters on it, 4 for a planeswalker,
it is lost to the nightmare.
"The immense brain that Mensis retrieved from the nightmare was indeed lined with eyes on the inside,
but they were of an evil sort, and the brain itself was terrible rotten."