Cheapest priced copy (Duskmourn: House of Horror Commander): $2.29 at Card Kingdom, near mint, their price list as of .
Rampaging Ferocidon 
Creature — Dinosaur · 3/3 · Rare · Special Guests · #8
Menace
Players can't gain life.
Whenever another creature enters, this creature deals 1 damage to that creature's controller.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
6 printings · $2.29 to $27.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duskmourn: House of Horror Commander | 167 | Rare | $2.29 | — |
| Ixalan Promos | 154s | Rare | — | $5.99 |
| Secret Lair Drop (Velociraptor) | 1390 | Rare | $27.99 | — |
| Secret Lair Drop (Velociraptor) | 1390★ | Rare | — | $19.99 |
| Special Guests | 8 | Rare | $5.99 | $6.99 |
| Ixalan | 154 | Rare | $2.99 | $4.49 |
4 rulings from Wizards of the Coast
- 29 September 2017Rampaging Ferocidon's last ability triggers whenever any player has a creature enter the battlefield, including you.
- 29 September 2017If an effect says to set a player's life total to a number that's higher than the player's current life total while Rampaging Ferocidon is on the battlefield, the player's life total doesn't change.
- 29 September 2017Spells and abilities that cause players to gain life still resolve while Rampaging Ferocidon is on the battlefield. No player will gain life, but any other effects of that spell or ability will happen.
- 29 September 2017If another creature enters the battlefield at the same time as Rampaging Ferocidon, its last ability triggers.