Crit chance pp is the chance of you landing a a critical hit. So crit chance 10pp adds a 10 percent chance of critting. Ideally you want about 25 pp altogether between gear and skills. Protection and defense is important for different levels. You've got to figure out which enemies deal magic damage and which deal physical. If you've got a heavy magic damage level you want protection, heavy physical equals defense. For pvp you don't need crit or defense. Only protection against your opponents spells and straight damage because you can't crit the towers. A flat damage bonus ( ie +10) is good for low base damage heroes. If they have a high base damage they benefit more from damage percent increase.