Clock Town

When you planeswalk to Clock Town, put three
time counters on it.
At the beginning of each upkeep, remove a time counter from Clock Town.
When the last time counter is removed from
Clock Town, destroy all nonland permanents,
then planeswalk.
Song of Time - Whenever chaos ensues, if Clock
Town has less than three time counters on it, put
a number of time counters on it equal to the difference.