The Lathnu Time I’ll Forget!

Anduin and Nythendra are playing in a Kaladesh/Aether Revolt Sealed PPTQ. On Anduin’s turn, he casts Lathnu Hellion. Nythendra has no response, and Anduin says “Gain 2 energy?” Nythendra nods approvingly. Anduin then asks if he can go to combat, and attacks with the Hellion and a Longtusk Cub. Nythendra says “no blocks”, and both players adjust life totals. Anduin then says “Go.” Nythendra untaps and draws a card, then proclaims “Hey, you didn’t get energy for the Longtusk Cub dealing damage to me!“ Anduin’s replies ”right, I completely forgot. I also forgot my Lathnu Hellion trigger.“ At this point Nythendra raises her hand and calls ”Judge!” What do you do?

Judges feel free to discuss this scenario on Judge Apps.

Answer

Anduin receives a Warning for Missed trigger for the Lathnu Hellion trigger. For the Longtusk Cub, Nythendra can let Anduin resolve the trigger now or let it stay missed.

For the Lathnu Hellion trigger, Nythendra gets the choice of either:
Resolve the default action the next time a player would receive priority
Do nothing and leave it missed