Time Eater

At the start of each player's upkeep, remove all
time counters from Time Eater.
Whenever a player casts a spell, add one time
counter to Time Eater.
Remove 6 time counters from Time Eater:
End the turn. (Exile all spells and abilities from the
stack. Discard down to your maximum hand size.
Damage wears off, and "this turn" and "until end of
turn" effects end.)