HP: 9,500
Grendel is a Ruminant-type enemy that you can find in the Mt. Gagazet caves or along the pathway to the Zanarkand Ruins. You need to capture five of each Ruminant-type enemy to unlock Juggernaut in the Species Conquest section of the Monster Arena.
Grendel can do a fairly heavy amount of damage to your party members. The best strategy is to have Wakka use 
Dark Attack or Dark Buster on them to blind them, which will prevent them from landing their physical attacks.
Kimahri can use 
Lancet on a Dual Horn to learn Fire Breath for his Ronso Rage Overdrive.
| Ability | Description |
|---|---|
 Sensor |
“Inflict darkness to evade its attacks. Piercing weapons are the way to go.” |
| Scan |
“Inflict darkness to hinder its attacks. Its Flame Ball is a powerful fire attack that hits all, but it needs to Charge before it’s released. Use poison and piercing weapons. Kimahri can learn Fire Breath.” |
Steal:
Hi-Potion (common)
Mega-Potion (x2) (rare)
Drops:
Ability Sphere (common)
Ability Sphere (x2) (rare)
Location
You can find them anywhere in the Mt. Gagazet caves or along the walkway to the Zanarkand Ruins.