Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Seething Song

Godo, Bandit Warlord

When Godo, Bandit Warlord enters, you may search your library for an Equipment card, put it onto the battlefield, then shuffle.
Whenever Godo attacks for the first time each turn, untap it and all Samurai you control. After this phase, there is an additional combat phase.

Ricochet Trap

If an opponent cast a blue spell this turn, you may pay {R} rather than pay this spell's mana cost.
Change the target of target spell with a single target.

Jeska's Will

Choose one. If you control a commander as you cast this spell, you may choose both instead.
• Add {R} for each card in target opponent's hand.
• Exile the top three cards of your library. You may play them this turn.

Cursed Mirror

{T}: Add {R}.
As Cursed Mirror enters, you may have it become a copy of any creature on the battlefield until end of turn, except it has haste.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Magnetic Theft

Attach target Equipment to target creature. (Control of the Equipment doesn't change.)

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.

Pyretic Ritual

The Reaver Cleaver

Equipped creature gets +1/+1 and has trample and "Whenever this creature deals combat damage to a player or planeswalker, create that many Treasure tokens."
Equip {3}

Twinflame Tyrant

Flying
If a source you control would deal damage to an opponent or a permanent an opponent controls, it deals double that damage instead.

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Red Elemental Blast

Choose one —
• Counter target blue spell.
• Destroy target blue permanent.

Have

Aggravated Assault

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)