Heh, I never used a two-handed staff. There's a one-handed staff of the judge – at the beginning, I leveled up the one-handed staff to 30% so I could more or less comfortably kill weak mobs, and then I went to join the monastery. After that, everything was easy.
I didn't really use the Summon spell much. I remember killing trolls by summoning about twenty skeletons and goblins. I remember not being able to kill a dragon by summoning the same number of adult skeletons; it regenerated faster than they could kill it.
However, I played as a mage for the very first time when I first played Gothic, and I did many things wrong due to my inexperience. And I think G2 was also my first RPG.
I won't Google it; I don't need to; I'm doing fine without it.
You also can't kill many orcs with the Fireball spell. In any case, neither a mage, nor a mercenary, nor a paladin can handle a large crowd in an open space. You either have to lure them out one by one or come up with something.
If only there was a Rain of Fire spell. But it can only be used in the sixth chapter, and it costs about 150 mana. By the end of the game, I had that much mana with all sorts of amulets, but again, I was a noob and developed my character incorrectly, because good mages finish G2 with 250-300 mana.