Why would you want to level up faster? Better stats,more runes and ability points, new items in shops. If you struggle with your current dungeon, consider it. It is more efficient to spend gold on XP upgrades rather than buying the best items in shop. The stats from leveling up have way bigger impact. The game will give you plenty of good equipment anyway if you are willing to explore.
- Enemies who are lower level than you yield less XP so I suggest you dont bother with enemies 3 levels below your champs.
- There are various XP bonuses you can notice after a battle ends, for example If you spend no mana during the battle, only overcharge (+ults), if your team is at full health at the end of the battle, multi-kills (finish multiple enemies with 1 ability, this one can almost double the XP so Id say its well worth the extra turns) There might be more but these are the ones Ive noticed so far.
- Some vendors sell meal that gives you XP bonus for a few battles (Barons rest). Its worth the investment, use it before boss fights.
- Enchanting – there is a level 10 armor enchantment that gives you 10% bonus XP. Consider buying the supplies from the lady in Slums Market if you dont have them.
- Enemies in some areas you have cleared before will scale after a certain stage in the game. (I noticed Grey Harbor so far but Im sure there is more).