Cheapest priced copy (Commander Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Tuya Bearclaw 
Legendary Creature — Human Warrior · 2/2 · Uncommon · Commander Masters · #360
Whenever Tuya Bearclaw attacks, it gets +X/+X until end of turn, where X is the greatest power among other creatures you control.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 360 | Uncommon | $0.35 | $0.49 |
| Commander Legends | 292 | Uncommon | $0.35 | $0.49 |
| Commander Legends | 612 | Uncommon | — | — |
2 rulings from Wizards of the Coast
- 10 November 2020The value of X is calculated as Tuya Bearclaw's ability resolves. If you control no other creatures at that time or if the greatest power among other creatures you control is 0 or less, X will be 0.
- 10 November 2020Once the ability resolves and the bonus is applied, that bonus won't change, even if the greatest power among other creatures you control does.