So do I get full XP when I kill a mob that has the red skull showing above it?
What are the level caps for each area?
Hard to say exactly. All you need to do is look at the color of the quest in your journal. If it's green, you're at level and will receive normal XP. If it's orange / red, you're under-leveled, perhaps dangerously so, and you'll probably have a miserable time but get a fair chunk of XP. If it's grey, you're over-leveled for it. It'll probably be a cakewalk, and you'll get little or perhaps no XP.
Hm. But I'm still in Velen, and the main quests I'm working on are level 6. I am level 12, almost 13. What went wrong? Is it because I did too many side quests at my level? If the world waits for me to complete main quests, why was this possible?
It's always worth another play-through!Not sure (don't remember the level breakdown of Velen, exactly -- guess it's nearly time for another TW3 playthrough!
As far as I know, Velen (and Skellige) contain so many side quests, if you wander off from the main story, it is very possible to slip above the suggested level, without trying too hard. A simple rule for quest levels is as follows: If you are more than 5 levels above or below a quest's level requirement, this will affect how much experience you receive. For example, if you are on level 13, and a quest is level 6, you will not receive full experience for completing it. However, if you are on level 13, and a quest is level 7 or 8, you should receive either full or partial experience for completing it.What went wrong? Is it because I did too many side quests at my level? If the world waits for me to complete main quests, why was this possible?