Cultivator Drone

Oracle Text

Devoid (This card has no color.)

T: Add C. Spend this mana only to cast a colorless spell, activate an ability of a colorless permanent, or pay a cost that contains C. (C represents colorless mana.)

Card Rulings

1/22/2016 Mana produced by Cultivator Drone may be used to cast any colorless spell, including most artifact spells, face-down spells, and spells with devoid.
1/22/2016 Some triggered abilities include a cost as part of their resolution. For example, Bearer of Silence’s ability says, in part, “When you cast Bearer of Silence, you may pay .” You may use mana produced by Cultivator Drone to help pay that cost. In fact, you could tap two Cultivator Drones to pay the entire cost.