Uldroc, Former of Spells 3UGW
Legendary Creature - Wizard
Whenever you cast an instant or sorcery spell, if it wasn't cast from exile, you may
have it lose all its other types and put it on the battlefield face down after it resolves. It becomes an X/X creature token, where X is its converted mana cost. It has "When this creature dies, you may exile it. If you do, cast this spell from exile without paying its mana cost." 3UGW, Exile a card from your hand: You may cast target instant or sorcery card in your graveyard without paying its mana cost.
"I'm never gonna give it up! I'm never gonna let him down! I'm gonna show to him that living spells are possible!" -Uldroc, Former of Spells
What are you going to do about the rules that prevent instant and sorcery cards from being put on the battlefield?
110.4. There are five permanent types: artifact, creature, enchantment, land, and planeswalker. Instant and sorcery cards can’t enter the battlefield and thus can’t be permanents. Some tribal cards can enter the battlefield and some can’t, depending on their other card types. See section 3, “Card Types.”
304.4. Instants can’t enter the battlefield. If an instant would enter the battlefield, it remains in its previous zone instead.
307.4. Sorceries can’t enter the battlefield. If a sorcery would enter the battlefield, it remains in its previous zone instead.
I think this could be solved / simplified with something like
"Whenever you cast an instant or sorcery spell, you may exile it. If you do, create an X/X "creature type" creature token, where X is equal to that spell's converted mana cost."
"Whenever a "creature type" leaves the battlefield, you may cast target instant or sorcery from exile with converted mana cost less than or equal to that creatures power."
This is kind of a work around of actually making the spells into creatures, but a replacement effect. It might need a bit of trimming on the wording, but overall I think it does exactly what you're looking for and dodges the ruling issues in question.
Again, another update. But just to note, the creature token themselves will have the "cast sorcery or instant from exile", NOT Uldroc, since that would mean they can simply counter the effect by playing removal on Uldroc. I did take your creature type advice though.
Can't you just make this ability something similar to manifest?
Private Mod Note
Rollback Post to RevisionRollBack
How i feel about competitive players and casual players in EDH: The competitive are german tourists, the casual are italian tourists, both in a italian beach. The italians asking themselves "why are the germans here?" make a legitimate question, the answer is because the beach is beautiful, no matter the country you came from. The italians wanting to ban the germans are dumb, because if the germans pay for their stay and follow the rules like everyone else, they have the right to be in the beach. Hovewer, if the germans started to ask themselves "why are the italians here?"... they would be dumb as hell.