Mass Ultimatum

(you cannot cast a legendary sorcery unless you control a
legendary creature or planeswalker)
{p/b} can be paid as {b} or half X life
{p/r} can be paid as {r} or half X life
Each player sacrifices X creatures.
They thought Kar was gone. We will show them the truth!
-Un-Kar, Leader of the Cult of Kar