Cheapest priced copy (Modern Masters 2017): $0.69 at Card Kingdom, near mint, their price list as of .
Damping Matrix 
Artifact · Rare · Mirrodin · #161
Activated abilities of artifacts and creatures can't be activated unless they're mana abilities.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.69 to $11.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Masters 2017 | 218 | Rare | $0.69 | $4.99 |
| Mirrodin | 161 | Rare | $0.69 | $11.99 |
3 rulings from Wizards of the Coast
- 14 March 2017Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keyword abilities, such as equip, are activated abilities and will have colons in their reminder text.
- 14 March 2017Damping Matrix’s ability affects only artifacts and creatures on the battlefield. Activated abilities that work in other zones (such as bloodrush or unearth) can still be activated. Triggered abilities (starting with “when,” “whenever,” or “at”) are unaffected.
- 14 March 2017A mana ability is an ability that produces mana, not an ability that costs mana.