Saw in Half

Destroy target creature. If that creature dies this way, its controller creates two tokens that are copies of that creature, except their power is half that creature's power and their toughness is half that creature's toughness. Round up each time.

Ardent Elementalist

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Salvager of Secrets

Mnemonic Wall

Defender
When this creature enters, you may return target instant or sorcery card from your graveyard to your hand.

Izzet Chronarch

Living Lightning

When this creature dies, return target instant or sorcery card from your graveyard to your hand.

Scribe of the Mindful

{1}, {T}, Sacrifice this creature: Return target instant or sorcery card from your graveyard to your hand.

Repository Skaab

Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, return target instant or sorcery card from your graveyard to your hand.

Revolutionist

When this creature enters, return target instant or sorcery card from your graveyard to your hand.
Madness {3}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Spellkeeper Weird

{2}, {T}, Sacrifice this creature: Return target instant or sorcery card from your graveyard to your hand.

Archaeomancer

Vexing Scuttler

Emerge {6}{U} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When you cast this spell, you may return target instant or sorcery card from your graveyard to your hand.