Reins of Power

Untap all creatures you control and all creatures target opponent controls. You and that opponent each gain control of all creatures the other controls until end of turn. Those creatures gain haste until end of turn.

Reverse Damage

The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.

Powerstone Minefield

Whenever a creature attacks or blocks, Powerstone Minefield deals 2 damage to it.

Will Kenrith

+2: Until your next turn, up to two target creatures each have base power and toughness 0/3 and lose all abilities.
−2: Target player draws two cards. Until your next turn, instant, sorcery, and planeswalker spells that player casts cost {2} less to cast.
−8: Target player gets an emblem with "Whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy."
Partner with Rowan Kenrith
Will Kenrith can be your commander.

Truefire Captain

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Truefire Captain is dealt damage, it deals that much damage to target player.

Land Tax

At the beginning of your upkeep, if an opponent controls more lands than you, you may search your library for up to three basic land cards, reveal them, put them into your hand, then shuffle.

Boros Reckoner

Whenever Boros Reckoner is dealt damage, it deals that much damage to any target.
{R/W}: Boros Reckoner gains first strike until end of turn.

Mirror Strike

All combat damage that would be dealt to you this turn by target unblocked creature is dealt to its controller instead.

Reflect Damage

The next time a source of your choice would deal damage this turn, that damage is dealt to that source's controller instead.

Reiterate

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Copy target instant or sorcery spell. You may choose new targets for the copy.

Aura Thief

Flying
When Aura Thief dies, you gain control of all enchantments. (You don't get to move Auras.)

Aether Flash

Whenever a creature enters, Aether Flash deals 2 damage to it.

Winds of Abandon

Exile target creature you don't control. For each creature exiled this way, its controller searches their library for a basic land card. Those players put those cards onto the battlefield tapped, then shuffle.
Overload {4}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Mischievous Quanar

{3}{U}{U}: Turn Mischievous Quanar face down.
Morph {1}{U}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Mischievous Quanar is turned face up, copy target instant or sorcery spell. You may choose new targets for that copy.

Magus of the Balance

{4}{W}, {T}, Sacrifice Magus of the Balance: Each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice creatures the same way.

Academy Ruins

{T}: Add {C}.
{1}{U}, {T}: Put target artifact card from your graveyard on top of your library.

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Vesuva

You may have Vesuva enter tapped as a copy of any land on the battlefield.

Day's Undoing

Each player shuffles their hand and graveyard into their library, then draws seven cards. If it's your turn, end the turn. (Exile all spells and abilities from the stack, including this card. Discard down to your maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Illusory Ambusher

Flash (You may cast this spell any time you could cast an instant.)
Whenever Illusory Ambusher is dealt damage, draw that many cards.

Parallectric Feedback

Parallectric Feedback deals damage to target spell's controller equal to that spell's mana value.

Dualcaster Mage

Flash
When Dualcaster Mage enters, copy target instant or sorcery spell. You may choose new targets for the copy.

Mandate of Peace

Cast this spell only during combat.
Your opponents can't cast spells this turn.
End the combat phase. (Remove all attackers and blockers from combat. Exile all spells and abilities from the stack, including this spell.)

Trove of Temptation

Each opponent must attack you or a planeswalker you control with at least one creature each combat if able.
At the beginning of your end step, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Dazzling Reflection

You gain life equal to target creature's power. The next time that creature would deal damage this turn, prevent that damage.

Rowan Kenrith

+2: During target player's next turn, each creature that player controls attacks if able.
−2: Rowan Kenrith deals 3 damage to each tapped creature target player controls.
−8: Target player gets an emblem with "Whenever you activate an ability that isn't a mana ability, copy it. You may choose new targets for the copy."
Partner with Will Kenrith
Rowan Kenrith can be your commander.

Sun Titan

Vigilance
Whenever Sun Titan enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Desertion

Counter target spell. If an artifact or creature spell is countered this way, put that card onto the battlefield under your control instead of into its owner's graveyard.

Jeskai Banner

{T}: Add {U}, {R}, or {W}.
{U}{R}{W}, {T}, Sacrifice Jeskai Banner: Draw a card.

Solar Blaze

Each creature deals damage to itself equal to its power.

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Thought Sponge

Flash
Thought Sponge enters with a number of +1/+1 counters on it equal to the greatest number of cards an opponent has drawn this turn.
When Thought Sponge dies, draw cards equal to its power.

Acidic Soil

Acidic Soil deals damage to each player equal to the number of lands they control.

Boros Fury-Shield

Prevent all combat damage that would be dealt by target attacking or blocking creature this turn. If {R} was spent to cast this spell, Boros Fury-Shield deals damage to that creature's controller equal to the creature's power.

Lightmine Field

Whenever one or more creatures attack, Lightmine Field deals damage to each of those creatures equal to the number of attacking creatures.

Settle the Wreckage

Exile all attacking creatures target player controls. That player may search their library for that many basic land cards, put those cards onto the battlefield tapped, then shuffle.

Leadership Vacuum

Target player returns each commander they control from the battlefield to the command zone.
Draw a card.

Cooperate

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Copy target instant or sorcery spell. You may choose new targets for the copy.

Refuse

Refuse deals damage to target spell's controller equal to that spell's mana value.

Refuse // Cooperate

Copy Enchantment

You may have Copy Enchantment enter as a copy of any enchantment on the battlefield.

Radiate

Choose target instant or sorcery spell that targets only a single permanent or player. Copy that spell for each other permanent or player the spell could target. Each copy targets a different one of those permanents and players.

Cerebral Vortex

Target player draws two cards, then Cerebral Vortex deals damage to that player equal to the number of cards they've drawn this turn.

Honorable Passage

The next time a source of your choice would deal damage to any target this turn, prevent that damage. If damage from a red source is prevented this way, Honorable Passage deals that much damage to the source's controller.

Comeuppance

Prevent all damage that would be dealt to you and planeswalkers you control this turn by sources you don't control. If damage from a creature source is prevented this way, Comeuppance deals that much damage to that creature. If damage from a noncreature source is prevented this way, Comeuppance deals that much damage to the source's controller.

Viashino Heretic

{1}{R}, {T}: Destroy target artifact. Viashino Heretic deals damage to that artifact's controller equal to the artifact's mana value.