Question : Can I support a city I plan to conquest with my myth units or does that rule about matching myth units still apply?
What happens if I sent the myth unit on the transport anyway ? Does the ship itself turn back or does ALL support turn back? Or does the game won't let me send the support in the first place?
basically, just to combine the two above, you can't support a city with myth units from a different god to the one being worshipped in that city, but any myth units you sent with your CS will stay in the city to defend your siege.
e.g. the town you want to conquer worships zeus and you send a CS with medusas to attack the city. if your CS lands then the medusas will stay to defend your siege even though it's a zeus city. now, if you sent 2 waves of support to your siege - 1 wave of pegusi and 1 wave of minotaurs, then the pegusi (and whatever was sent with them) will NOT land, but the minotaurs would land and defend your siege.
if you try to support a city with incorrect myths (e.g. sending medusas to a town which worships zeus) then your
entire support wave will return home after arriving and you'll get a report telling you something about your support not being able to land.