Dreadhorde Arcanist

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

Static Discharge

Starting intensity 3
Static Discharge deals damage equal to its intensity to any target. Then cards you own named Static Discharge intensify by 1.

Keldon Flamesage

Enlist
Whenever Keldon Flamesage attacks, look at the top X cards of your library, where X is Keldon Flamesage's power. You may exile an instant or sorcery card with mana value X or less from among them. Put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost.

Twinferno

Choose one —
• When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
• Target creature you control gains double strike until end of turn.