Then you are going to die. You cannot function without any magic at all in this game.
Even with a powerful, well-built character, ravenloft is one of the hardest campaigns there is. You will not be able to survive, much less meaningfully contribute without any actual powers.
If you still insist on doing this:
I assume for simplicity's sake other systems (initiation, binding, psionics, meldshaping) are not something you're interested in. If that's not the case, tell me what subsystems you like and I'll advise things in that vein.
One of the only classes that supports this kind of thing is the forsaker, which destroys the party's valuable loot for crappy dr and ability boosts, since you can't use magic or items.
If your gm's allowing all books, you might build a hulking hurler and throw (nonmagical) rocks at enemies (except incorporeal monsters, which there are a fair amount of in ravenloft. better leave those to the other pcs) instead of the normal +1 osmium yoyo hulking hurlers use.
ravenloft recommends your guy starts the campaign at level 6, and it will take them through about level 9 assuming they finish the whole campaign and do all the encounters.