#extra combat phase

[magicjudge]

For cards like Waves of Agression and others that give an extra combat step and are sorceries, if you cast them on another player's upkeep with Quicken or during some other time on their turn, what happens?

If it’s not a main phase when Waves of Aggression or another extra combat phase card resolves, then nothing happens. The card can only do anything if it resolves in a main phase.