Heroic Reinforcements

Create two 1/1 white Soldier creature tokens. Until end of turn, creatures you control get +1/+1 and gain haste. (They can attack and {T} this turn.)

Plains

Fleeting Effigy

Haste
At the beginning of your end step, return this creature to its owner's hand. (Return it only if it's on the battlefield.)
{2}{R}: This creature gets +2/+0 until end of turn.

Flamewake Phoenix

Flying, haste
This creature attacks each combat if able.
Ferocious — At the beginning of combat on your turn, if you control a creature with power 4 or greater, you may pay {R}. If you do, return this card from your graveyard to the battlefield.

Lorehold Charm

Choose one —
• Each opponent sacrifices a nontoken artifact of their choice.
• Return target artifact or creature card with mana value 2 or less from your graveyard to the battlefield.
• Creatures you control get +1/+1 and gain trample until end of turn.

Kellan, Planar Trailblazer

{1}{R}: If Kellan is a Scout, it becomes a Human Faerie Detective and gains "Whenever Kellan deals combat damage to a player, exile the top card of your library. You may play that card this turn."
{2}{R}: If Kellan is a Detective, it becomes a 3/2 Human Faerie Rogue and gains double strike.

Sun-Blessed Healer

Kicker {1}{W} (You may pay an additional {1}{W} as you cast this spell.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
When this creature enters, if it was kicked, return target nonland permanent card with mana value 2 or less from your graveyard to the battlefield.

Sunspine Lynx

Players can't gain life.
Damage can't be prevented.
When this creature enters, it deals damage to each player equal to the number of nonbasic lands that player controls.

Hop to It

Create three 1/1 white Rabbit creature tokens.

Descendant of Storms

Whenever this creature attacks, you may pay {1}{W}. If you do, it endures 1. (Put a +1/+1 counter on it or create a 1/1 white Spirit creature token.)

Antiquities on the Loose

Create two 2/2 red and white Spirit creature tokens. Then if this spell was cast from anywhere other than your hand, put a +1/+1 counter on each Spirit you control.
Flashback {4}{W}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mabel, Heir to Cragflame

Other Mice you control get +1/+1.
When Mabel enters, create Cragflame, a legendary colorless Equipment artifact token with "Equipped creature gets +1/+1 and has vigilance, trample, and haste" and equip {2}.

Monstrous Rage

Target creature gets +2/+0 until end of turn. Create a Monster Role token attached to it. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1 and has trample.)

How to Start a Riot

Target creature gains menace until end of turn. (It can't be blocked except by two or more creatures.)
Creatures target player controls get +2/+0 until end of turn.

Sure Strike

Target creature gets +3/+0 and gains first strike until end of turn. (It deals combat damage before creatures without first strike.)

Make Your Move

Destroy target artifact, enchantment, or creature with power 4 or greater.

Seedglaive Mentor

Vigilance, haste
Valiant — Whenever this creature becomes the target of a spell or ability you control for the first time each turn, put a +1/+1 counter on it.

Interjection

Target creature gets +2/+2 and gains first strike until end of turn.

Dauntless Veteran

Whenever this creature attacks, creatures you control get +1/+1 until end of turn.

Secret Rendezvous

You and target opponent each draw three cards.

Joined Researchers

First strike
At the beginning of each end step, if an opponent has more cards in hand than you, this creature becomes prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Joined Researchers // Secret Rendezvous

Resolute Reinforcements

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, create a 1/1 white Soldier creature token.

Hardened Academic

Flying, haste
Discard a card: This creature gains lifelink until end of turn.
Whenever one or more cards leave your graveyard, put a +1/+1 counter on target creature you control.

Duel Tactics

Duel Tactics deals 1 damage to target creature. It can't block this turn.
Flashback {1}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mountain

Rapier Wit

Tap target creature. If it's your turn, put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Draw a card.

Practiced Offense

Put a +1/+1 counter on each creature target player controls. Target creature gains your choice of double strike or lifelink until end of turn.
Flashback {1}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Swiftblade Vindicator

Double strike (This creature deals both first-strike and regular combat damage.)
Vigilance (Attacking doesn't cause this creature to tap.)
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Rocket Volley

Maelstrom Artisan

Haste
This creature enters prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)