Power Artifact

Oracle Text

Enchant artifact

Enchanted artifact's activated abilities cost 2 less to activate. This effect can't reduce the amount of mana an ability costs to activate to less than one mana.

Card Rulings

10/4/2004 Only affects the generic mana part of activation costs. Colored parts of mana costs are not affected.
10/4/2004 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.
7/15/2006 Can’t reduce Snow mana costs.
6/8/2016 Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.