Dreadhorde Arcanist

Trample
Whenever this creature attacks, you may cast target instant or sorcery card with mana value less than or equal to this creature's power from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Jarsyl, Dark Age Scion

Starting intensity 1
At the beginning of combat on your turn, you may cast a spell with mana value equal to Jarsyl, Dark Age Scion's intensity from your graveyard without paying its mana cost. If you do, Jarsyl intensifies by 1.