Cheapest priced copy (The Lost Caverns of Ixalan): $0.35 at Card Kingdom, near mint, their price list as of .
Contested Game Ball 
Artifact · Uncommon · The Lost Caverns of Ixalan · #251
Whenever you're dealt combat damage, the attacking player gains control of this artifact and untaps it.
{2}, {T}: Draw a card and put a point counter on this artifact. Then if it has five or more point counters on it, sacrifice it and create a Treasure token.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The Lost Caverns of Ixalan | 251 | Uncommon | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 10 November 2023Contested Game Ball's triggered ability triggers only once whenever you're dealt combat damage, no matter how many creatures deal combat damage to you at the same time.
- 10 November 2023In a Two-Headed Giant game, each player on the attacking team is an attacking player. When Contested Game Ball's first ability resolves, you'll choose which member of the attacking team gains control of it.
- 10 November 2023If point counters are put on Contested Game Ball some way other than its last ability, you won't sacrifice it or create a Treasure token. The check for five or more point counters happens only as the activated ability resolves.