Cheapest priced copy (Rivals of Ixalan): $0.49 at Card Kingdom, near mint, their price list as of .
Cacophodon 
Creature — Dinosaur · 2/5 · Uncommon · Rivals of Ixalan · #123
Enrage — Whenever this creature is dealt damage, untap target permanent.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.49 to $3.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Rivals of Ixalan | 123 | Uncommon | $0.49 | $3.99 |
2 rulings from Wizards of the Coast
- 19 January 2018If multiple sources deal damage to a creature with an enrage ability at the same time, most likely because multiple creatures blocked that creature, the enrage ability triggers only once.
- 19 January 2018If lethal damage is dealt to a creature with an enrage ability, that ability triggers. The creature with that enrage ability leaves the battlefield before that ability resolves, so it won’t be affected by the resolving ability.