This hunt becomes available any time after you have completed the Ancient City of Giruvegan and the Great Crystal. You should return to Balfonheim Port to speak to Reddas and have him join your party before starting this hunt as having Reddas in your party will be helpful.
Rena can be found in the western section of The Spiritwood in Eruyt Village. Use the map and the screenshot below to help you find her:
This Mark can be found in the Redolent Glade area of the Feywood which is where you initially fought Rafflesia. From Eruyt Village, just walk straight south through the Golmore Jungle into the Feywood.
Go south through the Walk of Flitting Rifts, the Walk of Stolen Truths and into Antiquity’s End where you can save your game and prepare for the battle against Malboro.
Level: 50
HP: 110,842
Steal: 
Malboro Flower (55%), Foul Liquid (10%), Virgo Gem (3%)
Wild Malboro will begin the battle with three additional Malboro enemies that are following it around. The best strategy for getting rid of them is to hit them all with an 
Aeroga with a character that has the 
Faith spell activated. One or two hits will kill them all quickly.
Make liberal use of the nearby Save Crystal to buff all of your party members in advance and then touch it again to refill your MP before engaging the Wild Malboro. Critical spells that you should come in with are Protect, Shell (to reduce the likelihood of statuses taking effect on your characters), 
Bubble (to prevent the Disease status effect), Bravery, 
Haste and Faith.
Equip all of your characters with accessories that will prevent some status effects (such as 
Black Belts or 
Bowline Sash). Use Dispel on Wild Malboro once all of the smaller Malboros are defeated to remove its beneficial status effects. You can also use 
Remedies instead of Esuna to get rid of status effects faster if you are having trouble with them.
A video of the battle in the Zodiac Age version is included below:
Return to Rena in Eruyt Village to obtain the rewards. The rewards for this Hunt include 4,600 gil and a 
Euclid’s Sextant. Don’t expect any kindness as a reward from the Viera though, they make that quite clear.
This Hunt is normally completed after Reddas has joined the party when they return to Balfonheim Port for the second visit. Click on the link to return to that section of the walkthrough.
