Vinrael in Heroes 5

All experience that hero gains after battles is increased by 2% per hero level.

Vinrael has two attributes that make him valuable to the Elves - he is unusually observant, and he has seen more hours of battle than any other Sylvan warrior. His keen eyes, and those of his falcons, rove constantly before, during, and after a battle, studying all the elements of troops, tactics, and terrain. Analyzing both his own and the enemy’s actions, he learns enormously from both sides' successes and errors.