The battlefield has a 30 minute time limit, up to 6 party members may enter, and it is uncapped. Buffs including TP are not lost upon entry, and experience points are lost from KO.
The Letter from Shikaree Y is lost upon entry. If the battle is not completed successfully, Despachiaire will give a new one after the next Conquest tally.
If this is your first time entering this battlefield. meaning you have the Letter from Shikaree Y) and you enter with others that have completed it before, having a different key item, the Letter from the Mithran Trackers), and if they are the ones to enter first, and you fail, you will not be able to obtain a new Key item until the next Conquest tally.
After successfully clearing the battlefield and waiting until the next Conquest tally, you may return to Despachiaire to obtain the new key item, Letter from the Mithran Trackers, which will allow you to repeat the battle.
If you defeat Shikaree X or Shikaree Z but not their pet and then you are defeated, the pet will not return to the original spawn locations, but will instead stay where it was. This can be dangerous because if you are defeated by the pet or are within their range for other reasons, it is not possible to be revived without being attacked by them. It should also be noted that no matter where any of the enemies are after going passive, if the pets engage a player character, the others will join in.