Cheapest priced copy (Alara Reborn): $0.49 at Card Kingdom, near mint, their price list as of .
Predatory Advantage 
Enchantment · Rare · Alara Reborn · #58
At the beginning of each opponent's end step, if that player didn't cast a creature spell this turn, create a 2/2 green Lizard creature token.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Alara Reborn | 58 | Rare | $0.49 | $0.79 |
3 rulings from Wizards of the Coast
- 1 May 2009Predatory Advantage’s ability has an “intervening ‘if’ clause.” That means (1) the ability won’t trigger at all unless the opponent whose turn it is didn’t cast a creature spell that turn, and (2) the ability will do nothing unless the opponent whose turn it is still hasn’t cast a creature spell by the time it resolves.
- 1 May 2009Predatory Advantage checks whether a player cast a creature spell, not whether a creature entered the battlefield under that player’s control. If that player cast a creature spell but you countered it, for example, you won’t get a Lizard token that turn.
- 1 May 2009In a Two-Headed Giant game, Predatory Advantage’s ability triggers twice at the end of the opposing team’s turn: once for each player. If neither of those players cast a creature spell that turn, you’ll get two Lizards. If one of those players cast a creature spell but the other didn’t, you’ll get one Lizard.