From levels 1 to 19, your hero gains base stats and useful bonuses. Levels 20 to 29 continue that growth with stronger challenges and new rewards.
Levels 30 to 255 focus on powerful gear and bonuses. Base stats stop increasing after level 29, but temporary boosts from abilities and equipment can raise them further.
Strength improves melee combat and helps with heavy weapons.
Dexterity improves agility, precision, dodging, and some combat actions.
Vitality increases health, endurance, and natural resistance to damage.
Perception helps you notice details, hidden objects, traps, nearby encounters, and danger.
Luck affects fortune, combat rolls, ability outcomes, critical hits, and some encounters. It does not increase with level, but items and abilities can change it.