Aim High

Untap target creature. It gets +2/+2 and gains reach until end of turn. (It can block creatures with flying.)

Aerial Volley

Aerial Volley deals 3 damage divided as you choose among one, two, or three target creatures with flying.

Acid Web Spider

Reach
When Acid Web Spider enters, you may destroy target Equipment.

Ancient Greenwarden

Reach (This creature can block creatures with flying.)
You may play lands from your graveyard.
If a land entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Galadriel, Light of Valinor

Alliance — Whenever another creature you control enters, choose one that hasn't been chosen this turn —
• Add {G}{G}{G}.
• Put a +1/+1 counter on each creature you control.
• Scry 2, then draw a card.

Aether Helix

Return target permanent to its owner's hand. Return target permanent card from your graveyard to your hand.

Aether Web

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1, has reach, and can block creatures with shadow as though they didn't have shadow. (Creatures with reach can block creatures with flying.)