When fighting monsters outside of your own character's level range, the following multipliers apply:
- Monster is 1 level above character: +15%
- Monster is 2 levels above character: +20%
- Monster is 3 or more levels above character: +25%
- Monster is 1 level below character: -10%
- Monster is 2 levels below character: -20%
- Monster is 3 levels below character: -30%
- Monster is 4 levels below character: -40%
- Monster is 5 levels below character: -50%
- [...] approaching 0 XP
Fighting monsters with a much higher level than your character does not actually grant a higher XP bonus beyond 25%. The only value that scales up after that point is the monster's base XP, which slowly rises with higher levels. This makes farming high level zones ineffective unless you can comfortably defeat enemies at a pace comparable to monsters close to your own level.
Tip: Since a monster's base XP value scales up linearly according to their level, fighting massively higher level monsters is much more valuable on low character levels compared to high character levels where the impact of each additional monster level is not as high compared to its total XP amount.