Angelsong

Prevent all combat damage that would be dealt this turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Argothian Treefolk

Prevent all damage that would be dealt to Argothian Treefolk by artifact sources.

Amulet of Kroog

{2}, {T}: Prevent the next 1 damage that would be dealt to any target this turn.

Arachnogenesis

Create X 1/2 green Spider creature tokens with reach, where X is the number of creatures attacking you. Prevent all combat damage that would be dealt this turn by non-Spider creatures.

Angel of Suffering

Flying
If damage would be dealt to you, prevent that damage and mill twice that many cards.

Alabaster Potion

Choose one —
• Target player gains X life.
• Prevent the next X damage that would be dealt to any target this turn.

Angel of Salvation

Flash; convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying
When Angel of Salvation enters, prevent the next 5 damage that would be dealt this turn to any number of targets, divided as you choose.

Argothian Pixies

Argothian Pixies can't be blocked by artifact creatures.
Prevent all damage that would be dealt to Argothian Pixies by artifact creatures.