Does Ruined Rex's deathknell ability deal damage before or after the healing step after combat?

According to the rules of Riftbound, Ruined Rex's Deathknell ability resolves after the healing step following combat.

While the process of resolving combat and cleanup involves several steps, the authoritative sequence is as follows:

1. Combat Damage Step: Combat damage is dealt to units (Rule 460.2.d).
2. Triggering Deathknell: During the Combat Special Cleanup, units with lethal damage (like Ruined Rex) trigger their Deathknell abilities. These triggers are added to the chain as Pending Items (Rule 808.1.d.2, Rule 323.4).
3. Killing Units: Units with lethal damage are killed and placed in the trash (Rule 323.5).
4. Healing: Surviving units on the battlefield are healed (Rule 461.1.a.1, FAQ #9786).
5. Resolution: Only after all units have been healed does the game return to the FEPR (Finalize, Execute, Pass, Resolve) process, at which point the pending Deathknell triggers on the chain are resolved (Rule 808.1.d.3, FAQ #9514, FAQ #9786).

Because healing occurs in Step 4 and the resolution of the Deathknell ability occurs in Step 5, Ruined Rex's damage cannot be used to "finish off" a unit that survived the combat damage, as that damage will be cleared by the healing step before the Deathknell effect executes.

This interpretation is based on official FAQ #9786 and FAQ #9514 regarding the timing of Deathknell and healing.