Normally, Gothic II is a difficult game (at least with the Night of the Raven expansion). Up until the halfway point, your character is extremely soft and squishy and deals very paltry amounts of damage. This is of course playing a physical attacker, such as a melee fighter or archer/crossbowman. Granted, around midway through you reach a point where all but the strongest mobs are a threat, but it takes a good amount of effort to reach said point.
As it turns out, it's so much harder playing a fire mage. For a long time, your magic is too weak to do more than slightly soften up your target, meaning your good old fashioned fighting prowess is what has to carry the day. Naturally, you'd think leveling your fighting abilities just a bit to hold you over until your magic isn't as weak would be a good idea, but that's a beginner's trap. Learning points are extremely valuable and not only is high level runecrafting extremely expensive, but also additional mana gets more and more expensive as you further level it up. This means that unless you're very careful to spend only on your magic abilities, you simply won't be strong enough to deal with the end game. So you have to just have to be very strategic about how you use your very limited magical prowess, and then hope you've weakened them enough to be able to clumsily put them down via melee. But that's not all. Runecrafting requires blank runes, of which there are only half as many in the game as there are possible spells. That means, you need to be very careful to only craft runes that you'll actually need, and to be especially conservative about crafting low level runes, as you want as many 5th and 6th circle runes as you possibly can.
I have to say, I love it. For a second play through, the additional challenge and more complex character building is pretty much perfect. For all it's weird controls and laughably bad voice acting, Gothic 2 has to be my favourite RPG by quite a wide margin.