Atomic Mushroom

When Atomic Mushroom enters the battlefield
exile all Lands on the battlefield.
At the beginning of each player's upkeep, that
player puts a scorch counter on a Land they
control then loses life equal to the total number
of scorch counters on Lands they control.
When Atomic Mushroom leaves the battlefield
return all Lands that were exiled by it. Each
player loses life equal to the number of Lands
they control returned this way.