Abjure

As an additional cost to cast this spell, sacrifice a blue permanent.
Counter target spell.

Aether Spike

Choose target spell. You get {E}{E} (two energy counters), then you may pay any amount of {E}. Counter that spell unless its controller pays {1} for each {E} paid this way.

Admiral's Order

Raid — If you attacked this turn, you may pay {U} rather than pay this spell's mana cost.
Counter target spell.

Amazing Acrobatics

Choose one or both —
• Counter target spell.
• Tap one or two target creatures.

Access Denied

Counter target spell. Create X 1/1 colorless Thopter artifact creature tokens with flying, where X is that spell's mana value.

Aang and La, Ocean's Fury

Reach, trample
Whenever Aang and La attack, put a +1/+1 counter on each tapped creature you control.

Aang, Swift Savior

Flash
Flying
When Aang enters, airbend up to one other target creature or spell. (Exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)
Waterbend {8}: Transform Aang.

Aang, Swift Savior // Aang and La, Ocean's Fury

Absolute Virtue

This spell can't be countered.
Flying
You have protection from each of your opponents. (You can't be dealt damage, enchanted, or targeted by anything controlled by your opponents.)

Adaptive Training Post

Whenever you cast an instant or sorcery spell, if this artifact has fewer than three charge counters on it, put a charge counter on it.
Remove three charge counters from this artifact: When you next cast an instant or sorcery spell this turn, copy it and you may choose new targets for the copy.

Absorb

Adric, Mathematical Genius

{2}{U}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
Ultimate Sacrifice — {1}{U}, Sacrifice Adric: Counter target activated or triggered ability.
Doctor's companion (You can have two commanders if the other is the Doctor.)