The vedalken embed such urns in their living artifact creations.

Commander 2018

Blinkmoth Urn

At the beginning of each player's precombat main phase, if Blinkmoth Urn is untapped, that player adds {C} for each artifact they control.

At the beginning of each player's first main phase, if Blinkmoth Urn is untapped, that player adds {C} for each artifact they control.

Commander 2016

At the beginning of each player's precombat main phase, if Blinkmoth Urn is untapped, that player adds {C} to his or her mana pool for each artifact he or she controls.

Mirrodin

At the beginning of each player's precombat main phase, if Blinkmoth Urn is untapped, that player adds {1} to his or her mana pool for each artifact he or she controls.