Twilight's Fall – a separate game. Twilight Imperium's expansions, mods and rules topics are not part of it.

Spark

After another player's unit uses Sustain Damage to cancel a hit produced by your units or abilities: Destroy that unit.
Action card

After another player's unit uses Sustain Damage to cancel a hit produced by your units or abilities:

Destroy that unit.

2in the deck
–chance to draw
Nocomponent action

Source: Twilight's Fall