MTG Salvation

That seems like a lot for porfing one of your existing creatures into a 5/5 flyer. Maybe if it was a lot cheaper to cast, or it didn't require either the discard or the sacrifice.

I'm sure it'll break some board stalls in limited at least.

First things first, yes, I get that this is an Uncommon, so the bar for it being playable is already pretty high. But as for your points, current standard doesn't see madness, flashback, or hellbent. Wider formats are a lot faster than the 6 CMC can afford. Aristocrat archetype decks have better payoff cards, with activations that aren't sorcery speed, nor one sided with their activation criteria. As for your final example, high risk beat sticks for low mana but high net cost are not unheard of. Avatar of Discord can do it off of ritual. Salvage Titan can do it off of cheerios.

The moment this gets you two demons, you've gone -4 in card advantage. For what? Two demons that can be cheaply answered in every color.

In standard, we've seen Demons that are better while netting card advantage at the same cost, better at cheaper cost with no drawback, or better with further less resource intensive cost. Historically, in the same rarity, same story.

Wesley is right. The absolute least this will do is break stalls in limited, and even that can take two turns when top decking. A last pick card for sure.

Its a core set uncommon. You bet its not as strong as Bolas's Citadel. It can turn an army of draft jank creatures into a usable army maybe. We all understand its getting zero constructed play.

Five mana turns every token you make thereafter into a 4/4 flying vigilant angel with no card disadvantage, not just at instant speed but as a state based action, and while dodging red removal.

Six mana with a black casting cost lets you play your library in exchange for life and can zot someone for 10 to close out a game.

Getting 2 demons requires paying 6 mana, having 2 other creatures to sacrifice, discarding 2 additional cards, and paying 4 life, and takes two turns since it can only be done once a turn without additional setup cards. Maybe there's a home somewhere in a commander deck for this, or in a low-tier modern constructed deck, but I doubt I'll ever see a single copy played on arena outside of limited.

...Both of you are joking, right? At 6 mana down, the moment this gets you two demons, you've gotten solid value. Discarding isn't a steep cost when you have madness, flashback, or hellbent synergy. Sacrificing a creature is pretty simple too if you have things like Doomed Traveler or Reef Worm. And of course, 2 life is the easiest thing in the world to pay. Forget that it's sorcery speed. This turns cards and creatures you don't need into pure value beatsticks.

Also, 1 mana for this instead of 6? Get out of town. I want you to think about why paying just 1 mana, 2 life, a creature and a card for a 5/5 flyer is bonkers.

Agreed, the innate card disadvantage in the ability cost is really unappealing, unless you can greatly take advantage of the discard/sac outlet. Even so, this seems way overcosted at 4BB; this could cost 1 mana and still seem way to costly given the sorcery speed restriction.

Kind of like a Skirsdag High Priest that doesn't die to all the same things the demons do, and it makes a demon immediately. Cost seems fair, maybe one too expensive, but it's uncommon.