Cheapest priced copy (Masters 25): $0.35 at Card Kingdom, near mint, their price list as of .
Primal Clay 
Artifact Creature — Shapeshifter · */* · Rare · Fourth Edition · #342
As this creature enters, it becomes your choice of a 3/3 artifact creature, a 2/2 artifact creature with flying, or a 1/6 Wall artifact creature with defender in addition to its other types. (A creature with defender can't attack.)
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
10 printings · $0.35 to $1.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Revised Edition | 271 | Rare | $0.49 | — |
| Fourth Edition Foreign Black Border | 342 | Rare | — | — |
| Fourth Edition | 342 | Rare | $0.49 | — |
| Fifth Edition | 395 | Rare | $0.49 | — |
| Classic Sixth Edition | 308 | Rare | $0.49 | — |
| Masters 25 | 228 | Common | $0.35 | $0.49 |
| Antiquities | 61 | Uncommon | $1.79 | — |
| Foreign Black Border | 271 | Rare | — | — |
| Magic 2013 | 210 | Uncommon | $0.35 | $0.49 |
| Summer Magic / Edgar | 271 | Rare | — | — |
3 rulings from Wizards of the Coast
- 19 March 2021If an object on the battlefield becomes a copy of Primal Clay, it copies the values determined by its enters-the-battlefield replacement effect.
- 19 March 2021While not on the battlefield, Primal Clay is a 0/0 creature card. It doesn't have flying or defender.
- 19 March 2021If an object enters the battlefield as a copy of Primal Clay, it copies the values determined by its enters-the-battlefield replacement effect, but its power and toughness are determined by the copy's own enters-the-battlefield replacement effect. This can cause you to have a 3/3 creature with flying, or a 1/6 creature with flying and defender, for example.