If Karthus, Eternal dies together with another unit with Deathknell, does that Deathknell still trigger an additional tile?

Question

Accepted Answer

Yes, the other unit's **Deathknell** effect will still trigger an additional time.

According to **RiftJudge FAQ #5353** and **FAQ #8974**, this interaction works because Karthus, Eternal's ability ("Your [Deathknell] effects trigger an additional time") is a **passive ability**, not a triggered ability.

### Why this works:
*   **Passive vs. Triggered:** Because Karthus's ability is passive, it does not need to "evaluate" its own trigger condition at the moment of death. It simply applies its effect to the game state as long as Karthus is on the board.
*   **Simultaneous Events:** When Karthus and another unit with Deathknell die at the same time (for example, due to a board wipe or combat damage), Karthus's passive effect is still active at the exact moment the other unit's Deathknell trigger is created.
*   **Result:** The other unit's Deathknell triggers once for its own death, plus one additional time due to Karthus's passive ability.

This is distinct from triggered abilities (like those of *Viktor, Leader*), which cannot trigger if the source leaves the board at the same time the trigger condition is met, because those abilities must evaluate their own trigger condition at that moment. Since Karthus is a passive effect, he successfully modifies the Deathknell trigger of the other unit as it occurs.