Plains

Chronomaton

{1}, {T}: Put a +1/+1 counter on Chronomaton.

Tomb of the Spirit Dragon

{T}: Add {C}.
{2}, {T}: You gain 1 life for each colorless creature you control.

Ghostfire Blade

Equipped creature gets +2/+2.
Equip {3}
Ghostfire Blade's equip ability costs {2} less to activate if it targets a colorless creature.

Signal Pest

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
Signal Pest can't be blocked except by creatures with flying or reach.

Memnite

Chief of the Foundry

Other artifact creatures you control get +1/+1.

Tempered Steel

Artifact creatures you control get +2/+2.