Do units heal before Deathknell abilities resolve after combat?

Ruling: Yes, units heal before Deathknell abilities resolve. During combat resolution, the FEPR process is skipped and the Resolution Step begins immediately. Units with lethal damage trigger their Deathknell abilities (which become pending items) and are killed during Combat Cleanup. Then all surviving units are healed as part of the Combat Special Cleanup. Only after all outstanding tasks complete does the game return to FEPR, at which point the pending Deathknell triggers are placed on the chain and resolve.

Sequence:

• Combat damage is dealt (Rule 460.2.d)
• FEPR is skipped; proceed to Resolution Step (Rule 460.3)
• Combat Cleanup begins (Rule 461.1)
• Units with lethal damage trigger Deathknell (pending items) and die
• All surviving units are healed (Rule 461.1.a.1)
• Remaining combat tasks complete (Rules 461.2-461.7)
• FEPR resumes and Deathknell triggers resolve

Nuances:

• Deathknell abilities cannot finish off units that took non-lethal combat damage, as that damage is healed before Deathknell resolves.
• If your units survive combat damage but are killed by Deathknell after healing, you will not have units on the battlefield when control is established.