OH!

For some insane reason, I assumed you were referring to the ToF Lich.

You can't beat the 1st encounter?

Dude, just get Harm3, it's 1 more level, and then try to cut corners elsewhere (That's what I'd do anyway, but I'm a slacker. You can persevere.)

Here's some inspiration:

I am now officially tackling the solo Thief challenge (again...)

Lv 4. 20 tries. 19 uneventful failures. 2 Critical hits. Garland is finally defeated.
(Actually, I beat him once, and had 6 HP with no heals. I ran into a Spider on the 3 steps to the princess and was killed)