Power Artifact
Enchantment — Aura
Enchant artifact
Enchanted artifact's activated abilities cost 
less to activate. This effect can't reduce the mana in that cost to less than one mana.
Douglas Shuler
Antiquities (ATQ)
• #11Rulings
Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.
(wotc • 2016-06-08)
Can't reduce Snow mana costs.
(wotc • 2006-07-15)
Only affects the generic mana part of activation costs. Colored parts of mana costs are not affected.
(wotc • 2004-10-04)
Can be placed on artifacts with no or zero activation costs, but this has no effect on them. It does not increase the cost to one.
(wotc • 2004-10-04)
Rulings
Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.
(wotc • 2016-06-08)
Can't reduce Snow mana costs.
(wotc • 2006-07-15)
Only affects the generic mana part of activation costs. Colored parts of mana costs are not affected.
(wotc • 2004-10-04)
Can be placed on artifacts with no or zero activation costs, but this has no effect on them. It does not increase the cost to one.
(wotc • 2004-10-04)