Limited Infinity

Unlimited mana, one spell per turn

Abilities can be used infinitely

Your cards work how you want them to, with very limited exceptions

Defensive player will win ties with a given activated ability (infinite), but two offensive infinites pointed at the same target will trump one defensive ability, and so on.

Morph, being an alternate casting cost, is a spell for the turn. Embalm, being an activated ability, is not.

Cards played as their backs (Brisela, Mishra, Urza) have combined CMC of their fronts. Ormendahl has no CMC, but costs your spell for the turn.