Cheapest priced copy (Commander 2015): $0.49 at Card Kingdom, near mint, their price list as of .
Kessig Cagebreakers 
Creature — Human Rogue · 3/4 · Rare · Innistrad · #189
Whenever this creature attacks, create a 2/2 green Wolf creature token that's tapped and attacking for each creature card in your graveyard.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
5 printings · $0.49 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 187 | Rare | $0.49 | — |
| Commander Anthology | 122 | Rare | $0.49 | — |
| Innistrad | 189 | Rare | $0.49 | $2.99 |
| Jumpstart 2022 | 681 | Rare | $0.49 | — |
| Midnight Hunt Commander | 142 | Rare | $0.49 | — |
3 rulings from Wizards of the Coast
- 22 September 2011Although the tokens are attacking, they were never declared as attacking creatures (for purposes of abilities that trigger whenever a creature attacks, for example).
- 22 September 2011You count the number of creature cards in your graveyard when the triggered ability resolves.
- 22 September 2011You declare which player or planeswalker each token is attacking as you put it onto the battlefield. It doesn't have to be the same player or planeswalker Kessig Cagebreakers is attacking.