Adaptive Shimmerer

Flash
This creature enters with three +1/+1 counters on it.

Grumgully, the Generous

Each other non-Human creature you control enters with an additional +1/+1 counter on it.

Ainok Artillerist

This creature has reach as long as it has a +1/+1 counter on it. (It can block creatures with flying.)

Adaptive Sporesinger

Vigilance
When this creature enters, choose one —
• Target creature gets +2/+2 and gains vigilance until end of turn.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Aberrant

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Trample
Heavy Power Hammer — Whenever this creature deals combat damage to a player, destroy target artifact or enchantment that player controls.

Aether Vial

At the beginning of your upkeep, you may put a charge counter on this artifact.
{T}: You may put a creature card with mana value equal to the number of charge counters on this artifact from your hand onto the battlefield.