"Battle For The Ruins" Fast Levelling Glitch (Patreon)

The Demon Invasion World Quest "Battle For The Ruins" in Aszuna allows the player to use a "arcane bomb" aoe ability which almost two-shots powerful mobs. Levelling through grinding mobs is very fast with this ability.

This Invasion Quest is a "fill up the bar" type quest. When the bar reaches 100% the arcane bomb ability vanishes, presumably to prevent the type of fast levelling exploiters would naturally attempt. However, there is a relatively simple workaround. Simply join a group, any group, on the "custom" tab of group finder. 

While in a group any credit towards quest objectives is suspended. This allows you to keep the arcane bomb ability throughout the entire duration of the demon invasion. Because of its simplicity, it is quite simple to automate grinding-the bomb does substantially more damage than your own abilities powerful as you may be. 

The "Dreadflame Magus" mobs (red dranei females) offer the most xp. They have a ranged attack which is best interrupted-this causes them to close in for melee allowing you the chance to kite multiple maguses into your arcane bomb aoe.