Deadly Combination

When Deadly Combination enters the battlefield,
if you control cards named Toxic Gas and
Poisonous Gas, sacrifice them. If you do, search
your library for a Halt planeswalker or find a
Result card from outside the game and cast it
without paying its mana cost. Halt planeswalkers
enter the battlefield with X additional loyalty. If
you control a Halt planeswalker when Deadly
Combination enters the battlefield, instead your
opponent may mill four cards or lose 1 life.
Repeat this process X times.