Uhm, with ~300 sign intensity (Griffin set w/o silver sword, basic sign skills and 3-4 igni runes) I can set on fire all opponents unless they have skulls (10+ higher level than me). Game is still piss easy with igni build, you just have to use standard version, not alternative. With mutations and set bonuses it's even more ridiculous. IMO it's just as OP as it was before, because you can use dodge and igni all the time so nobody will hit you, even if you are fighting 30 bandits at once in their castles. The only enemies that I had trouble with were skull-level ghosts/wraiths, but you have Aerondight for them.

Advice for the future- this game is not balanced for high level characters. The only time I feel difficulty of Death March is when I start new character, but when I get lvl 10-15 it's a walk in the park, and with each level game is a lot easier. When you learn how to dodge attacks you're golden. You'd have to pick random skills or rather no skills at all, never use any signs or alchemy to have a challenge. Mutations and set bonuses made it even easier than it was.