Doomskar

Destroy all creatures.
Foretell {1}{W}{W} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Jeskai Student

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

Whirlwind Denial

For each spell and ability your opponents control, counter it unless its controller pays {4}.

Mordenkainen's Polymorph

Until end of turn, target creature becomes a Dragon with base power and toughness 4/4 and gains flying. (It loses all other creature types.)

Student of Ojutai

Whenever you cast a noncreature spell, you gain 2 life.

Lotus-Eye Mystics

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Lotus-Eye Mystics enters, return target enchantment card from your graveyard to your hand.

Raff, Weatherlight Stalwart

Whenever you cast an instant or sorcery spell, you may tap two untapped creatures you control. If you do, draw a card.
{3}{W}{W}: Creatures you control get +1/+1 and gain vigilance until end of turn.

Kwende, Pride of Femeref

Double strike
Creatures you control with first strike have double strike.

Dreadful as the Storm

Target creature has base power and toughness 5/5 until end of turn. The Ring tempts you.

Narset, Enlightened Master

First strike, hexproof
Whenever Narset, Enlightened Master attacks, exile the top four cards of your library. Until end of turn, you may cast noncreature spells from among those cards without paying their mana costs.

Commander Liara Portyr

Whenever you attack, spells you cast from exile this turn cost {X} less to cast, where X is the number of players being attacked. Exile the top X cards of your library. Until end of turn, you may cast spells from among those exiled cards.

Glorious Gale

Counter target creature spell. If it was a legendary spell, the Ring tempts you.

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.

Half-Elf Monk

Vigilance
Stunning Strike — {1}{W}, {T}: Tap target creature.

Dragon's Eye Sentry

Smite

Seeker of the Way

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

Blustersquall

Tap target creature you don't control.
Overload {3}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Sanctify

Destroy target artifact or enchantment. You gain 3 life.

Monk of the Open Hand

Flurry of Blows — Whenever you cast your second spell each turn, put a +1/+1 counter on Monk of the Open Hand.