Voidwatch is a battle system in Final Fantasy XI.
The player must be at least level 75, and have an Adventurer's Certificate, a Voidstone, and Stratum Abyssite. The latter two items can be obtained from a Voidwatch Officer located in various cities.
Voidwatch battles have several unique mechanics. There is a time limit of 30 minutes for all battles.
Once the battle is won, a Riftworn Pyxis will temporarily appear at the Planar Rift's location. All players who participate in the battle will receive Experience Points and cruor from it, depending on the battle's location and tier. If a voidstone is used, the base values will be multiplied by the player's yellow (EXP) and green (cruor) spectral alignments. However, experience points and cruor are not obtained from Provenance battles.
Various armor and weapons are available as well, along with atmacite and periapt.