If you kill a unit with Deathknell using Hook, and Hook's ability plays a Karthus (who affects Deathknell triggers), do you get two Deathknell triggers?

Ruling: You only get one Deathknell trigger. The unit is killed at the beginning of resolving Hook's ability, before Karthus could be banished and played, so Karthus's effect is not active when the Deathknell trigger occurs.

Sequence:

• Hook's ability begins resolving
• The unit with Deathknell is killed, triggering its Deathknell ability
• Karthus is then banished and played by Hook's effect
• Karthus's ability becomes active only after Hook's trigger fully resolves

Nuances:

• Even if the order were reversed, Karthus would only be pending until Hook's trigger resolves, so his ability still wouldn't be in effect for the Deathknell trigger