Stairway to Heaven

{t}: put a stair counter on Stairway to Heaven,
unless any opponent pays {x}, where X is the
number of stair counters on Stairway to Heaven
plus one.
If there are 5 or more stair counters on Stairway
to Heaven, exile it. You win the game, unless
each opponent discards their hand.
At the end of each phase, remove all stair
counters from Stairway to Heaven.