You can obtain this Hunt after you have defeated Judge Bergan after completing the events at the Stilshrine of Miriam and returning back to Mt Bur-Omisace for the second time.
Warrior Guromu can be found in the Lull of the Land area of Jahara on the south side of the zone.
The Mindflayer is located in the Phase 1 Dig area of Henne Mines. Warp to the Henne Mines by way of an orange Save Crystal, travel north and go through the doorway that leads back to the North Entrance.
Travel south into the Phase 1 Shaft and then south again into Phase 1 Dig. Mind Flayer can be found towards the southern section of the zone. Note that all characters must have more than 90% of their MP for it to spawn.
Level: 35
HP: 31,161
Steal: 
Pebble, 
Float Mote, 
Vanishga Mote
Mindflayer is one of the more difficult Hunts from a strategy point of view. It has a move in its arsenal called Time Requiem which will inflict the 
Stop status effect on all of your party members. There is a good chance that, even if all of your party members are hit with the Stop status effect, that you will survive and potentially recover. But you risk having to constantly dig yourself out of a hole and will have to over heal in between just to stay alive.
Once inflicted with Stop, Mindflayer will also cast 
Blizzara and then hit physically as well. Make sure that you keep 
Shell on all of your party members for the duration of the battle. Use any items, armor or accessories that you have that raise Magick Power as this will help your party members resist the status effect.
There are no items available currently that can prevent Stop if you are attempting this fight as early as possible, but if you are attempting it later in the game, you can pick up a 
Power Armlet accessory and equip it on your party members.
You can also use the 
Nihopalaoa and 
Remedy trick to inflict Berserk and Slow on Mindflayer to make the battle much easier. Check out the Nihopalaoa Accessory trick section for more information.
A video of the battle in the Zodiac Age version is included below:
Return to Warrior Guromu in Jahara to receive your reward which includes 2,200 gil and a 
Carmagnole.
