Elvish Doomsayer

When Elvish Doomsayer dies, each opponent discards a card.

Brallin, Skyshark Rider

Partner with Shabraz, the Skyshark (When this creature enters the battlefield, target player may put Shabraz into their hand from their library, then shuffle.)
Whenever you discard a card, put a +1/+1 counter on Brallin, Skyshark Rider and it deals 1 damage to each opponent.
{R}: Target Shark gains trample until end of turn.

Dragonlord's Servant

Dragon spells you cast cost {1} less to cast.

Genasi Enforcers

Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token that's a copy of this creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
{1}{R}: Creatures you control named Genasi Enforcers get +1/+0 until end of turn.

Arena Trickster

Whenever you cast your first spell during each opponent's turn, put a +1/+1 counter on Arena Trickster.

Dragonspeaker Shaman

Dragon spells you cast cost {2} less to cast.

Null Caller

{3}{B}, Exile a creature card from your graveyard: Create a tapped 2/2 black Zombie creature token.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Trailblazing Historian

Haste
{T}: Another target creature gains haste until end of turn.

Plaguecrafter

When Plaguecrafter enters the battlefield, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Flameheart Werewolf

Whenever Flameheart Werewolf blocks or becomes blocked by a creature, Flameheart Werewolf deals 2 damage to that creature.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Flameheart Werewolf.

Kessig Forgemaster

Whenever Kessig Forgemaster blocks or becomes blocked by a creature, Kessig Forgemaster deals 1 damage to that creature.
At the beginning of each upkeep, if no spells were cast last turn, transform Kessig Forgemaster.

Kessig Forgemaster // Flameheart Werewolf

Dragonmaster Outcast

At the beginning of your upkeep, if you control six or more lands, create a 5/5 red Dragon creature token with flying.

Ardent Dustspeaker

Whenever Ardent Dustspeaker attacks, you may put an instant or sorcery card from your graveyard on the bottom of your library. If you do, exile the top two cards of your library. You may play those cards this turn.

Tovolar's Magehunter

Whenever an opponent casts a spell, Tovolar's Magehunter deals 2 damage to that player.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Tovolar's Magehunter.

Mondronen Shaman

At the beginning of each upkeep, if no spells were cast last turn, transform Mondronen Shaman.

Mondronen Shaman // Tovolar's Magehunter

Ardent Elementalist

When Ardent Elementalist enters the battlefield, return target instant or sorcery card from your graveyard to your hand.

Incendiary Oracle

{1}{R}: Incendiary Oracle gets +1/+0 until end of turn.
If a creature dealt damage by Incendiary Oracle this turn would die, exile it instead.

Lightning Visionary

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Spellrune Howler

Whenever you cast an instant or sorcery spell, Spellrune Howler gets +2/+2 until end of turn.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Spellrune Painter

Whenever you cast an instant or sorcery spell, Spellrune Painter gets +1/+1 until end of turn.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)