MagisterCultuum
Great Sage
If a Regicide option were added, Basium, Hyborem, and Auric (probably the mortal version instead of the god) would have to be their civ's "king unit."
Hemah's Mind: New Feature needs to be designed for this one. Looks just like a forest, even claims to be a forest (ideally just pick some random tiles so the map is suitably covered and they are neither feature nor improvement and there is no indication of their true nature, but the property is disabled if a city is founded there). But acts like a Barbarian Hall of Mirrors (can create an illusion duplicate of any hostile unit (read - any non-Barbarian unit) within 1 tile of the feature). Illusionary constructs start with a duration of 5 and become permanent after winning any battle.
Tenacious: When a Civilization's last city is taken, they are granted control of the farthest away Barbarian City and all remaining units are relocated to that tile + Civilization Hero is granted if not currently alive
Kill the king- Each civ, including the player, has a "King" unit that is immune to marksman. Civ ceases to exist after king dies and all cities and units turn barb.
Protect the capital- I dunno if this is possible, but make it so other players cannot tell which city is their capital. When civ's capital is lost, civ loses. Pretty similar to king idea above.
Independence!- You start on an already occupied world as a breakaway province of a civ. You have just declared independence and start at war with your motherland. Enemies of motherland will help you through gifting units (Im not sure if gifting was ever put back in ffh), ceasing trade, etc, kinda like the french in the American Rev.
Hell world- basium and hyborem can be selected as starting random ai civs. AC starts at 50.
EDIT: ninjad by MC!