Bastion Protector

Commander creatures you control get +2/+2 and have indestructible.

Eldrazi Monument

Creatures you control get +1/+1 and have flying and indestructible.
At the beginning of your upkeep, sacrifice a creature. If you can't, sacrifice this artifact.

Keleth, Sunmane Familiar

Whenever a commander you control attacks, put a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)

Call for Unity

Revolt — At the beginning of your end step, if a permanent left the battlefield under your control this turn, put a unity counter on this enchantment.
Creatures you control get +1/+1 for each unity counter on this enchantment.

Day of Destiny

Legendary creatures you control get +2/+2.

Venerated Loxodon

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.)
When this creature enters, put a +1/+1 counter on each creature that convoked it.

Bloodsworn Steward

Flying
Commander creatures you control get +2/+2 and have haste.

Benalish Marshal

Dictate of Heliod

Felidar Retreat

Landfall — Whenever a land you control enters, choose one —
• Create a 2/2 white Cat Beast creature token.
• Put a +1/+1 counter on each creature you control. Those creatures gain vigilance until end of turn.

Bolt Hound

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever this creature attacks, other creatures you control get +1/+0 until end of turn.

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Commander's Insignia

Creatures you control get +1/+1 for each time you've cast your commander from the command zone this game.

Cavalier of Flame

{1}{R}: Creatures you control get +1/+0 and gain haste until end of turn.
When this creature enters, discard any number of cards, then draw that many cards.
When this creature dies, it deals X damage to each opponent and each planeswalker they control, where X is the number of land cards in your graveyard.

Angel of Invention

Flying, vigilance, lifelink
Fabricate 2 (When this creature enters, put two +1/+1 counters on it or create two 1/1 colorless Servo artifact creature tokens.)
Other creatures you control get +1/+1.

Animation Module

Whenever one or more +1/+1 counters are put on a permanent you control, you may pay {1}. If you do, create a 1/1 colorless Servo artifact creature token.
{3}, {T}: Choose a counter on target permanent or player. Give that permanent or player another counter of that kind.

Gird for Battle

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

Rograkh, Son of Rohgahh

First strike, menace, trample
Partner (You can have two commanders if both have partner.)

Aurelia, Exemplar of Justice

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, choose up to one target creature you control. Until end of turn, that creature gets +2/+0, gains trample if it's red, and gains vigilance if it's white.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Victory's Envoy

At the beginning of your upkeep, put a +1/+1 counter on each other creature you control.

Supply Runners

When this creature enters, put a +1/+1 counter on each other creature you control.