Crosis's Attendant

{1}, Sacrifice Crosis's Attendant: Add {U}{B}{R}.

Urza's Mine

{T}: Add {C}. If you control an Urza's Power-Plant and an Urza's Tower, add {C}{C} instead.

Anticognition

Counter target creature or planeswalker spell unless its controller pays {2}. If an opponent has eight or more cards in their graveyard, instead counter that spell, then scry 2.

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Alexi's Cloak

Flash
Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)

Urza's Power Plant

{T}: Add {C}. If you control an Urza's Mine and an Urza's Tower, add {C}{C} instead.

Arcbound Slasher

Modular 4 (This creature enters with four +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
Riot (This creature enters with your choice of an additional +1/+1 counter or haste.)

Antagonize

Target creature gets +4/+3 until end of turn.

Arcbound Worker

Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Counterspell

Aboshan's Desire

Enchant creature
Enchanted creature has flying.
Threshold — Enchanted creature has shroud as long as seven or more cards are in your graveyard. (It can't be the target of spells or abilities.)

Arcbound Stinger

Flying
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Ashnod's Transmogrant

{T}, Sacrifice Ashnod's Transmogrant: Put a +1/+1 counter on target nonartifact creature. That creature becomes an artifact in addition to its other types.

Urza's Tower

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

Anti-Magic Aura

Enchant creature
Enchanted creature can't be the target of spells and can't be enchanted by other Auras.

Apprentice Wizard

Aura Finesse

Attach target Aura you control to target creature.
Draw a card.

Agent of Stromgald

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Aura Flux

Other enchantments have "At the beginning of your upkeep, sacrifice this enchantment unless you pay {2}."

Betrayal

Enchant creature an opponent controls
Whenever enchanted creature becomes tapped, you draw a card.

Sol Ring

Artifact Blast

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Teach by Example

When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Blastfire Bolt

Blastfire Bolt deals 5 damage to target creature. Destroy all Equipment attached to that creature.

Armory of Iroas

Whenever equipped creature attacks, put a +1/+1 counter on it.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Arcane Signet

Bestial Fury

Enchant creature
When Bestial Fury enters, draw a card at the beginning of the next turn's upkeep.
Whenever enchanted creature becomes blocked, it gets +4/+0 and gains trample until end of turn.