Cheapest priced copy (Commander Masters): $0.39 at Card Kingdom, near mint, their price list as of .
Mace of the Valiant 
Artifact — Equipment · Rare · Throne of Eldraine · #314
Equipped creature gets +1/+1 for each charge counter on this Equipment and has vigilance. (Attacking doesn't cause it to tap.)
Whenever a creature you control enters, put a charge counter on this Equipment.
Equip {3}
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.39 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 41 | Uncommon | $0.39 | $0.79 |
| Throne of Eldraine | 314 | Rare | $0.49 | — |
| Foundations Jumpstart | 221 | Rare | $0.49 | — |
| Phyrexia: All Will Be One Commander | 78 | Rare | $0.49 | — |
One ruling from Wizards of the Coast
- 4 October 2019The equipped creature has vigilance even if Mace of the Valiant has no charge counters on it.