Level Sync is a system with which players in a party can reduce their level to cap at that of any of the party members. The leader of the party can choose to Level Sync the party by going to the party menu, then choosing level sync, and finally choosing the level sync target (level 10 or above). The levels of all party members will immediately be capped at that of the target party member, and all buffs will be removed, so take care if this is done near aggressive monsters. The level sync target will be denoted with a red dot to the right of their name in the party list, and all players will receive the level sync status icon.
Level Sync can also be removed by the leader through the menu ("Level Sync Off" option), but once you choose to remove the sync status, you must wait 30 seconds for your level to be uncapped. If the level sync target changes zone, leaves the party, or disconnects, the level sync status will be removed after 30 seconds.
Equipped gear and weapons from higher levels will not be removed during level sync, but the statistics of the gear will be reduced significantly and unique statistics (such as ability enhancement statistics) will not function at all, so it is generally still optimal to utilize gear from the proper level.
One of the notable uses of level sync is for Trial of the Magians. As Trial of the Magians requires monsters to yield experience points, it is generally easier to do these trials at lower levels when possible as lower level monsters at Easy Prey difficulty (10-30) tend to die far faster than their higher level counterparts. Since the weapon can still be equipped with level sync status on, the kills will still count towards the trial, even though many of the weapon's statistics will not be available.
Level Sync can also be used for lower level experience points parties as members will receive experience points as if they were at the lower level. Note that the level sync target must remain alive and within experience points range for members of the party to receive experience points from battles.