Cheapest priced copy (Dominaria United): $0.35 at Card Kingdom, near mint, their price list as of .
Coral Colony 
Creature — Wall · 1/4 · Uncommon · Dominaria United · #45
Defender
{1}{U}, {T}: Target player mills X cards, where X is the number of creatures you control with defender. (To mill a card, a player puts the top card of their library into their graveyard.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dominaria United | 45 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 9 September 2022The number of creatures with defender you control is counted when the ability resolves.