An epic level in the case of Divinity II is 30, and should not offer up the greatest of challenges unless you rush through the game oblivious to any sidequests and the experience mechanics.
A few things to keep in mind regarding this:
- Experience is finite. Meaning a killed enemy will not respawn.
- Experience recieved pr. enemy will gradually lower the higher level you reach. There is no way around this, so don't worry about it.
- Quest experience will not be affected by your level.
- Taking the skill Wisdom will give you an experience boost on monsters as well as quests, but the skill have level requirements.
- Taking the skill Mindread will lower the experience cost of reading minds, and also have level requirements.
- Using mindread costs experience (in a nifty debt system; you won't get negative exp, but will have to pay back the cost of a mindread before you recieve new exp). If you only choose the important minds to read; for more skillpoints and stats, and skip the 'nice to know' and loot related ones, you will level up quicker.
With these parameters in mind, the most bang for your buck when maximizing experience gain, is to clear out monsters and complete quest objectives first to level up as much as you can within a given area. Use the new levels and skillpoints on wisdom and mindread (for the useful mindreads) as far as you can go, THEN turn in the quests you have already completed for a maximum experience reward.
If you are thorough in using the experience mechanics to your advantage, you will probably reach level 30 about 80% way through the game. The practical 'maxlevel' on the 360 is closer to 40, with the average finnish level around 34-36.
If all else fails, there is one viable experience glitch in Aleroth City inside the temple, where you can make enemies respawn and still give exp. Look it up in a walkthrough or full guide if needed.