I... guess you could reprint the 4-mana instant Mnemonic Nexus as a 3-colour 3-mana sorcery, if a set had a significant 3-colour theme like Shards of Alara did.

Seems more like it would be Bant colors, though.

Yeah it would fit better in Bant. And given the right setting is the cost changed enough to allow the drop to common?

Tri-color cards are quite rare at common, and I'm not sure whether this effect is okay at common or not. It's not really about power level. I mean, even Elixir of Immortality is uncommon, and it's pretty simple.

This is an effect that would normally not do anything on Limited, which makes it dubious as a common. If there was a lot of graveyard effects in the set - more than Return to Ravnica which had the Golgari, perhaps as much as Innistrad or Odyssey - then it could be a relevant common - but at that point, making it tricolour makes it hard for most decks to use again...

What about costing it at or something similar?

We're saying that the effect isn't something that should appear at common, not that it's improperly costed.

"If there was a lot of graveyard effects in the set - more than Return to Ravnica which had the Golgari, perhaps as much as Innistrad or Odyssey - then it could be a relevant common - but at that point, making it tricolour makes it hard for most decks to use again..." ~ Alex

So it could be common "Tri-color cards are quite rare at common, and I'm not sure whether this effect is okay at common or not. It's not really about power level. I mean, even Elixir of Immortality is uncommon, and it's pretty simple."~ L2i0n0k7

Yes Elixir of Immortality is uncommon but it also gives you 5 life and puts the card itself back in your library.

Given that a heavy graveyard interactive set would need a simple graveyard hate at common I'm trying to figure out what a good cost would be.

As easy to cast as possible. Which tri-colour definitely isn't. Relic of Progenitus would do nicely. (Huh, that's been reprinted at uncommon, but it was originally common.) Heck, Tormod's Crypt could be common. Charging three different colours of mana for graveyard hate is just weird.

Both of your examples remove things from the grave yard so you can't use them. The card I've built while clearing the grave yard at least gives a chance to use them again.

In some ways, it's easier to get stuff back from graveyard than library. Admittedly; this does promote continual recursion, which exile does not.

There's still no reason for this to be gold-costed. You'd rarely want this effect; so it's already a niche card (and so if it's at common will cause much tearing up of cards) making it nigh-impossible to cast is just cruel.

Ok. What about making it a colorless spell? This card can; help decks against mill (though the other player gets the mill cards back into his or her library, it helps decks get thing back from the graveyard that might not be able to otherwise whilst slowing down decks that can make use of cards in their graveyard, it is a good way to thwart effects that search for on put a card on top of the library, and it also thwarts scry effects. I think that I'm going to just make it uncommon and colorless. but I'm not sure of the cost.

To be honest it sounds like you should just reprint Reminisce or Mnemonic Nexus.

Card has been changed. Card was "~WGU Sorcery - uncommon Each player shuffles his or her graveyard into his or her library."