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

Epiphany Hollow

After a puppeted player activates this system, replace up to 2 of that player's infantry on a planet they control with your infantry; those units coexist.
The ObsidianUnit – Structure – Monument

Monument

After a puppeted player activates this system, replace up to 2 of that player's infantry on a planet they control with your infantry; those units coexist.

Source: Monuments