Level Sync for Grind PT's.

Level Sync for (callable) NPC Companion.

Level Sync for R25 Dungeon. (optional, not forced)

Level Sync for "Recommended Level" quests. (optional, not forced)

Level Sync for LeveQuests (linking only, not for solo)

Level Sync for Behest.

Level Sync for future PvP content.

Level Sync for future PvE content.

Level Sync for future Company Crafting Quests.

Level Sync for future AF/Relic gear Boss Fights.

Level Sync for all content past, present and future that you can/want/have to do with others. (all optional, of course)