Urza's Rebuff

Choose one —
• Counter target spell.
• Tap up to two target creatures.

Gather the Townsfolk

Create two 1/1 white Human creature tokens.
Fateful hour — If you have 5 or less life, create five of those tokens instead.

Serum Visions

Sky Diamond

Clowning Around

Create two 1/1 white Clown Robot artifact creature tokens, then roll a six-sided die. If the result is equal to or less than the number of Robots you control, create a 1/1 white Clown Robot artifact creature token.

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.

Stonybrook Schoolmaster

Whenever Stonybrook Schoolmaster becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.

Dramatic Reversal

Untap all nonland permanents you control.

Hard Evidence

Create a 0/3 blue Crab creature token.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Archaeomancer

When Archaeomancer enters, return target instant or sorcery card from your graveyard to your hand.

Boomerang

Return target permanent to its owner's hand.

Hindering Light

Counter target spell that targets you or a permanent you control.
Draw a card.

Spiritual Visit

Create a 1/1 colorless Spirit creature token.
Splice onto Arcane {W} (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.)

Azorius Cluestone

{T}: Add {W} or {U}.
{W}{U}, {T}, Sacrifice Azorius Cluestone: Draw a card.

Afterlife

Destroy target creature. It can't be regenerated. Its controller creates a 1/1 white Spirit creature token with flying.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Master's Call

Create two 1/1 colorless Myr artifact creature tokens.

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Prescient Chimera

Flying
Whenever you cast an instant or sorcery spell, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Azorius Locket

{T}: Add {W} or {U}.
{W/U}{W/U}{W/U}{W/U}, {T}, Sacrifice Azorius Locket: Draw two cards.

Cruel Witness

Flying
Whenever you cast a noncreature spell, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Vodalian Arcanist

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell.

Azorius Signet

Cenn's Enlistment

Create two 1/1 white Kithkin Soldier creature tokens.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Apprentice Wizard

Rootborn Defenses

Populate. Creatures you control gain indestructible until end of turn. (To populate, create a token that's a copy of a creature token you control.)

Charge of the Mites

Choose one —
• Charge of the Mites deals damage equal to the number of creatures you control to target creature or planeswalker.
• Create two 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block." (Players dealt combat damage by them also get a poison counter.)