Bonkers. This only costs two mana? I could very easily have a turn-two Sharuum the Hegemon followed by a Blightsteel Colossus, all for a simple Faithless Looting or something similar.

I guess it could cost 3. At 4 you might as well just reanimate it. I don't have an issue with having a strong rare.

A Sharuum or Blightsteel Colossus that can be taken out by a simple Shock or Wring Flesh, admittedly.

Looks strong, certainly, but you'll need to build a deck around it. I could certainly see Artifact Reanimator being a thing in a format with this, but that does already lay quite some constraints (need White, plus a looting or discarding colour, plus a bunch of fatty artifacts, plus a plan for what to do if you don't draw an Academy Curator).

I think this is proobably fine.

May I instead suggest cards that cost a lot and benefits greatly from entering and/or leaving play? Careful Study plus Spine of Ish Sah makes a pretty strong Stone Rain. This plus Sundering Titan, and a way to sacrifice the Curator should mean game against a lot of decks. Magister Sphinx seems like a solid way to deal 10 damage for .

I'd like to make a couple of comments regarding the concerns you guys have brought up.

@Sharuum/Blightsteel Combo

First, Blightsteel is never in the graveyard long enough to be a target for this card unless you've stifled the trigger and if you've used another card to get to the point at which you're pulling off this three card combo then you deserve to get your rewards. I can't see this combo going off in anything but Commander so that's not a problem from my POV. EDH is full of broken combos.

@Looting/Spine and similar Combos

Thats another three card combo, having played LD decks I can tell you that if you're using three cards to get a one mana cheaper stone rain, you're doing it wrong. There will always be rediculous combos when you're creating new cards but that doesn't stop R&D from designing new powerful cards and it shouldn't stop us. We should more concerned about in-block degenerate combos, which I don't think this is one.

I think this would only really be a problem in older formats, which is hard for me to judge because I know next to nothing about them.

This would be extremely powerful in Modern, I'm pretty sure. Depending on the cards in Standard, it might be very strong there, as well.

would it help if it were a noncreature artifact?

Yes, I think that would be much more sensible. I mean, just imagine this on turn 2 with a Magister Sphinx. Yikes.

To be fair that would also imply you did something to get the Magister Sphinx in your Graveyard. You don't just start with what you want in your Graveyard, you have to spend cards to do it.

Mm, true. But there's a large difference betwen 'three card combo' and 'three part combo'. Three card combos are tough to pull off, since it requires aligning three individual cards. 'Ginormous creatures with solid etbs' is a part. Discarding a card is a part. You can do that by playing one out of a selection of cards that will allow you to discard a card. If the effect is good enough, I would expect 12x of that part to appear in your deck, making it as reliable as a single Plains in a two-color deck.

That, and you don't even need a part to discard a card. If the effect is good enough (like dealing 10 damage to an opponent in one swing), then go to 8 cards in hand, end the turn and discard a card. That's really simple to do.

A classic example of this in action would be the deck called "Life" from somewhere around 2002. The parts were terrible, but if part 'A', part 'B' and part 'C' were all fulfilled (Creature that increases toughness by being targeted, a way to infinitely target that creature, and sacrifice a creature to gain life equal to toughness), then the deck went to infinite life, and was nigh impossible to beat. It would regularly go off by turn 3.

This isn't that, since I don't think you can get as explosive as Life did, and Academy Curator is a card, not a part. But you should be careful, none the less. Playtesting should tell you a lot. If we're talking straight odss, I'm guessing drawing and playing this card, and getting a monster in the graveyard by round 3 (if you went second) would happen about 40% of the time. (48% to draw one Academy Curator out of 9 card, minus the odds for two lands, and one of 12 monsters.) If you want the Sphinx specifically, you'll get that and an Academy Curator about 30% of the time.

I see that you can repeatedly imprison this in a Helvault to get creature and artifact ETB and LTB triggers for 1 mana each time. Not the most efficient thing you can do with this, I think, but the starting draft of an engine.

We can change it noncreature artifact if you guys are really concerned about its potential as is.

Magister Sphinx? So you all think it's going to break the game to first turn, happen to have the right spell and the sphinx in the right spot to put it in your graveyard, the Curator to play turn 2, and then be able to deal ten extra damage somehow? Because the sphinx is not reliable, every deck has either creature kill, fliers, artifact kill, or all of the above. This card is pushed but is by no means broken. I would like to see it at 3 mana just because its a really solid value, but I wouldn't call it broken.

Non-creature artifact makes this unplayable IMO, I don't think it'd be insane for this to cost 3.