Does Riftbound have a concept of last known information? Specifically, if Yasuo Remorseful's attack trigger is on the stack and he is killed before it resolves, does his trigger deal damage based on his might when he died, when the ability triggered, or does it deal no damage?

Ruling: Riftbound does not have a concept of last known information. When a triggered ability resolves, "here" refers to the current location of the source unit at resolution time, not where it was when the ability triggered. If the source unit has left the battlefield, the ability cannot evaluate properly and deals no damage.

Sequence:

• Yasuo attacks and his trigger goes on the stack
• Yasuo is killed before the trigger resolves
• On resolution, "here" checks where Yasuo currently is
• Since Yasuo is no longer on the battlefield, the ability cannot evaluate and deals 0 damage

Nuances:

• This works differently from MTG's last known information rules
• For abilities that don't reference the source's stats (like dealing a fixed amount), if the source moves to a different battlefield before resolution, the ability still functions at the source's new location
• "Here" is treated as a natural language pointer to the current location of the source game object at resolution time
• For spells played from hidden, "here" refers to where the spell was played from (this is explicitly codified in the rules)