Pheres-Band Warchief

Vigilance, trample
Other Centaur creatures you control get +1/+1 and have vigilance and trample.

Hydra's Growth

Enchant creature
When Hydra's Growth enters the battlefield, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.

Reap What Is Sown

Put a +1/+1 counter on each of up to three target creatures.

Lagonna-Band Trailblazer

Heroic — Whenever you cast a spell that targets Lagonna-Band Trailblazer, put a +1/+1 counter on Lagonna-Band Trailblazer.

Blossoming Sands

Blossoming Sands enters the battlefield tapped.
When Blossoming Sands enters the battlefield, you gain 1 life.
{T}: Add {G} or {W}.

Centaur Battlemaster

Heroic — Whenever you cast a spell that targets Centaur Battlemaster, put three +1/+1 counters on Centaur Battlemaster.

Centaur's Herald

{2}{G}, Sacrifice Centaur's Herald: Create a 3/3 green Centaur creature token.

Plains

Forest

Chronicler of Heroes

When Chronicler of Heroes enters the battlefield, draw a card if you control a creature with a +1/+1 counter on it.

Gaea's Gift

Put a +1/+1 counter on target creature you control. It gains reach, trample, hexproof, and indestructible until end of turn. (It can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Conclave Mentor

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on that creature instead.
When Conclave Mentor dies, you gain life equal to its power.