Cheapest priced copy (Ravnica: City of Guilds): $0.49 at Card Kingdom, near mint, their price list as of .
Molten Sentry 
Creature — Elemental · */* · Rare · Ravnica: City of Guilds · #136
As this creature enters, flip a coin. If the coin comes up heads, this creature enters as a 5/2 creature with haste. If it comes up tails, this creature enters as a 2/5 creature with defender.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.49 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica: City of Guilds | 136 | Rare | $0.49 | $1.99 |
2 rulings from Wizards of the Coast
- 1 October 2005If a creature enters copying Molten Sentry, that creature's controller flips a coin to see what the copy will be.
- 1 October 2005If a creature that's already on the battlefield copies Molten Sentry, it becomes a copy of whatever Molten Sentry already is (either a 5/2 creature with haste or a 2/5 creature with defender).