Slash the Ranks

Destroy all creatures and planeswalkers except for commanders.

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.)

Rograkh, Son of Rohgahh

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

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Bastion Protector

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

Arcane Signet

Codsworth, Handy Helper

Commanders you control have ward {2}.
{T}: Add {W}{W}. Spend this mana only to cast Aura and/or Equipment spells.
{T}: Attach target Aura or Equipment you control to target creature you control. Activate only as a sorcery.

Bloodsworn Steward

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

Timely Ward

You may cast Timely Ward as though it had flash if it targets a commander.
Enchant creature
Enchanted creature has indestructible.

Vexilus Praetor

Flash
Vigilance
Aegis of the Emperor — Commanders you control have protection from everything.

Command Beacon

{T}: Add {C}.
{T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

Norn's Choirmaster

Flying, first strike
Whenever a commander you control enters or attacks, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Kediss, Emberclaw Familiar

Whenever a commander you control deals combat damage to an opponent, it deals that much damage to each other opponent.
Partner (You can have two commanders if both have partner.)

Loyal Unicorn

Vigilance
Lieutenant — At the beginning of combat on your turn, if you control your commander, prevent all combat damage that would be dealt to creatures you control this turn. Other creatures you control gain vigilance until end of turn.