With the new rules update, can you chain Janna to a Deathknell trigger to remove damage before a unit is killed?

Ruling: No, you cannot chain Janna during combat cleanup to prevent a unit from dying. During combat cleanup, chain items cannot be resolved, so Deathknell goes on as a pending item but you cannot react until after cleanup is complete, at which point the unit has already been put in the trash.

Sequence:

• Combat damage is assigned
• Combat cleanup begins (no reactions allowed during this phase)
• Units with lethal damage die
• Remaining units heal
• Deathknell triggers are added as pending items
• Cleanup completes
• You can now react, but the unit is already dead

Nuances:

• You could react with Janna after Deathknell triggers are finalized, but by that point units have already healed per special cleanup rules
• Deathknell units save all their info before death, so they can still trigger their effects properly