Cheapest priced copy (Shadows over Innistrad): $0.35 at Card Kingdom, near mint, their price list as of .
Gatstaf Arsonists // Gatstaf Ravagers 
Creature — Human Werewolf // Creature — Werewolf · 5/4 · Common · Shadows over Innistrad · #158
At the beginning of each upkeep, if no spells were cast last turn, transform this creature.
Menace (This creature can't be blocked except by two or more creatures.)
At the beginning of each upkeep, if a player cast two or more spells last turn, transform this creature.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Shadows over Innistrad | 158 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 8 April 2016To trigger the Werewolf's back face's transform ability, a single player must have cast two or more spells during the previous turn. If multiple players each cast just one spell during the previous turn, the ability won't trigger.
- 8 April 2016The abilities that transform a Werewolf back and forth look at the entire previous turn, even if the Werewolf with that ability wasn't on the battlefield for some or all of that turn.