Can you play Shen after a Deathknell trigger during combat cleanup to maintain control of the battlefield?

Ruling: Yes, you can play Shen after a Deathknell trigger during combat cleanup. The Special Cleanup (which triggers Deathknell) occurs before clearing the Contested status from the battlefield, allowing you to respond with Shen while still controlling the battlefield.

Sequence:

• Combat cleanup begins with Special Cleanup being invoked
• Deathknell triggers during Special Cleanup and goes on the Chain
• A new cleanup occurs after Deathknell becomes a Legal Item on the Chain
• After this cleanup completes, the game is in a Closed state and the defending player gets priority
• The defending player can play Shen at this point
• Only after this does the battlefield's Contested status get cleared

Nuances:

• This ruling is based on Chinese FAQ clarification that Special Cleanup and clearing Contested status are separate sequential steps, not simultaneous
• The validity of this ruling was questioned as the Chinese FAQ may predate the 1.1 English CRD update, leaving the final answer uncertain
• This interaction could make battlefields effectively unconquerable with recurrable reaction speed units like Teemo via Swift Scout