When Nocturne is revealed, how does the timing work for playing him - does he get played immediately during cleanup after the revealing effect resolves, or only after the entire chain resolves during an open state with priority?

Ruling: When Nocturne is revealed, he is immediately banished and becomes a pending item. After the effect that revealed him finishes resolving, during the cleanup step, you finalize him onto the chain by paying the cost (or choosing not to pay and keeping him banished).

Sequence:

• Nocturne is revealed during an effect's resolution
• He is immediately banished and becomes pending
• The revealing effect finishes resolving
• Cleanup happens immediately
• During cleanup, you finalize Nocturne onto the chain by paying the power cost
• You may choose not to pay the cost and keep him banished

Nuances:

• The cost is paid during finalization in cleanup, not when he is banished
• You do not need to wait for the entire chain to resolve or for an open state with priority
• The "may" wording suggests you can choose not to pay the cost and leave him banished
• Nocturne's ability is a passive ability