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

Professional Intrigue

After you perform a tactical action in a non-home system, you may move 1 of your infantry on the game board into coexistence on a planet in that system. When a player ends your units' coexistence on a planet, they must discard 1 action card, if able.
Li-Zho DynastyBreakthrough

After you perform a tactical action in a non-home system, you may move 1 of your infantry on the game board into coexistence on a planet in that system.

When a player ends your units' coexistence on a planet, they must discard 1 action card, if able.

SynergyWarfareBiotic

Source: Discordant Stars