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

Hostile World

After a player commits ground forces to land on a planet you control: Roll a number of dice equal to that planet's resource value, for each result of 6 or greater, produce 1 hit against those ground forces.
Action card

After a player commits ground forces to land on a planet you control:

Roll a number of dice equal to that planet's resource value, for each result of 6 or greater, produce 1 hit against those ground forces.

1in the deck
–chance to draw
Nocomponent action

Source: Uncharted Space