Cheapest priced copy (Outlaws of Thunder Junction): $0.35 at Card Kingdom, near mint, their price list as of .
Stubborn Burrowfiend 
Creature — Badger Beast Mount · 2/2 · Uncommon · Outlaws of Thunder Junction · #184
Whenever this creature becomes saddled for the first time each turn, mill two cards, then this creature gets +X/+X until end of turn, where X is the number of creature cards in your graveyard.
Saddle 2 (Tap any number of other creatures you control with total power 2 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Outlaws of Thunder Junction | 184 | Uncommon | $0.35 | $0.49 |
7 rulings from Wizards of the Coast
- 12 April 2024An ability that triggers when a creature “attacks while saddled” will trigger only if that creature was saddled when it was declared as an attacker.
- 12 April 2024“Saddled” isn’t an ability that a creature has. It’s just something true about that creature. It won’t stop being saddled until the turn ends or it leaves the battlefield.
- 12 April 2024If a permanent becomes a copy of a saddled Mount, the copy won’t be saddled.
- 12 April 2024The value of X is determined as Stubborn Burrowfiend’s triggered ability resolves.
- 12 April 2024You may activate a permanent’s saddle ability even if that permanent is already saddled.
- 12 April 2024Creatures with saddle can attack or block as normal even if they aren’t saddled.
- 12 April 2024“Saddle N” means “Tap any number of other untapped creatures you control with total power N or greater: This permanent becomes saddled until end of turn. Activate only as a sorcery.”