This came up in a casual playtest a couple days ago, which made me really thankful I could tell the players an upfront “I don't know.”
Amy has a
Silverblade Paladin paired with a
Champion of the Parish. Bob has a
Precinct Captain. Amy swings with both her creatures; Bob blocks Silverblade Paladin with the Captain.
Neither player does anything before First Strike damage, so Champion does its first strike damage to Bob, and the Paladin and Captain hit each other with first strike damage. State-based effects are checked, and the Paladin and Captain are destroyed. Therefore, the Champion no longer has double strike nor first strike.
Now it's time to assign normal combat damage. The Champion should, in theory, assign normal damage here as if the paladin had never existed, but something tells me this is wrong somehow. If this were correct, it could be a viable play in some weird corner case to have a creature with first strike lose its abilities after first strike damage happens, giving it de facto double strike, and I can't convince myself that's right.
I appreciate any reply to clear this up for me.
Thanks,
Ben