How does Ekko Recurrent's death trigger interact with The Zero Drive and Karthus Eternal? Can you recycle Ekko then banish him, or banish then recycle? Can you get runes back twice with Karthus?

Ruling: When Ekko dies with Zero Drive, you get multiple Deathknell triggers on the chain (two from Ekko, one from Zero Drive), but you can only successfully resolve one that affects Ekko. You must choose to either banish him OR recycle him and ready your runes - you cannot do both. You cannot recycle Ekko from banishment, and you cannot recycle him a second time once he's already in your deck.

Sequence:

• Three Deathknell triggers go on the chain: Ekko, Ekko, Zero Drive
• You choose the order to resolve them
• You can play reactions between each effect resolution
• If you recycle Ekko first, the banish trigger whiffs (invalid target)
• If you banish Ekko first, you cannot recycle from banishment
• If you recycle Ekko first, the second Ekko trigger also whiffs (cannot recycle from deck)

Nuances:

• Ekko's recycle ability is compulsory, not optional
• You cannot recycle from banishment because effects that reference cards in banishment only do so by means of also putting the cards there, and the default zone for effects is a board zone unless specified
• With Karthus, you can only get your runes back once since Ekko can only successfully recycle himself once