Can both be revived because of the double Deathknell effect of Karthus on Glasc Mixologist when my opponent plays Singularity on my Glasc Mixologist and Karthus, Eternal?

Question

Accepted Answer

Yes, both **Glasc Mixologist** and **Karthus, Eternal** will trigger their *Deathknell* effects (if they have them), and because **Karthus, Eternal** is on the board when the *Deathknell* triggers occur, the *Deathknell* effects will trigger an additional time.

However, there is a critical distinction: **Karthus, Eternal** does not have a *Deathknell* ability himself. Based on the card data retrieved, **Karthus, Eternal** has a passive ability that modifies *other* *Deathknell* effects.

### Sequence of Events
1. **Singularity** is played, targeting **Glasc Mixologist** and **Karthus, Eternal**.
2. **Singularity** resolves, dealing 6 damage to both units.
3. Both units have lethal damage (Glasc Mixologist has 5 Might, Karthus has 3 Might) and are marked for death.
4. The game enters the **Cleanup** phase.
5. **Deathknell Triggers:**
   - **Glasc Mixologist** has a *Deathknell* ability. Because **Karthus, Eternal** is on the board at the moment of death, the *Deathknell* triggers twice (once base + one additional time from Karthus).
   - **Karthus, Eternal** does not have a *Deathknell* ability, so he does not trigger one.
6. The two **Glasc Mixologist** *Deathknell* triggers are added to the chain as pending items.
7. Both units are moved to the trash.
8. The chain resolves, allowing you to resolve the *Deathknell* effect of **Glasc Mixologist** twice.

### Important Nuances
* **Karthus's Passive:** According to **RiftJudge FAQ #8974**, Karthus's ability is a passive ability, not a triggered ability. It remains active at the moment of death, allowing the *Deathknell* of the other unit to trigger twice.
* **Karthus's own Deathknell:** Since **Karthus, Eternal** does not have a *Deathknell* ability, he does not trigger one himself. If you had another unit with *Deathknell* on the board, it would also trigger twice.
* **Resolution:** You will resolve the *Deathknell* effect of **Glasc Mixologist** twice, allowing you to play up to two units from your trash that meet the cost requirements (cost no more than 3 and no more than [A]).

This is my interpretation based on the provided card text and rules regarding passive abilities and *Deathknell* timing. No official FAQ exists for this specific combination of cards, but it follows the established logic for Karthus's passive interaction with *Deathknell*.