Caught in the Crossfire

When Caught in the Crossfire enters the
battlefield it deals X damage to every legal target
and each player may search their library for a planeswalker card with converted mana cost X or
less, reveal it and put it onto the battlefield under
their control. Whenever a creature you control
attacks it and any blocking creatures take X
damage where X is equal to the total life you lost
due to this spell. When at most one player
controls a planeswalker sacrifice Caught in the Crossfire and deal X damag