Memory loss can affect skills/features?

[Yael]

A new campaign will start soon, it is a game based on the Dark Souls game franchise. I've never played it myself, but my friend (who will be the DM) loves it, so he wanted to do this game for blablah reason. Anyway, as thread says, he wants to roll d%s to determine how much memory we retain from our former life (we are supposed to be dead or something.) Now, I wanted to play a chronoshifter (homebrewed class, not by me), but I was planning a background as a cartographer (ranks in profesion and craft), but acording to the DM, we lose memory, would this acount as a penalty? Also, knowledges? My own ability to use my class features? He told us that we could even acquire memories that are not from us, so, could this affect?

[Xerlith]

This is purely houserules territory - and this question can be answered only by "Ask your DM". I'd say your class features and knowledges stay, but who knows.

[Kazudo]

I would imagine that it would, at the very least, allow you to reroll any failed Knowledge checks or Spellcraft checks (to determine spells in a spellbook specifically).

[Yael]

I thought the magical "Ask your DM" would appear; however, how would you homebrew this or just balance it? Because, maybe a sorcerer who forgot how to cast its spells, or a druid that forgot that she can wild shape... I just don't buy it.

[Mnemnosyne]

The closest thing I know of to actual rules on the topic is the programmed amnesia spell, which allows negative levels to be bestowed upon a subject by erasing their memory. The negative levels never result in permanent level loss, but can only be restored by reversing the spell.

[Slipperychicken]

Sometimes significant memory loss is represented with XP drain. Perhaps you'd all wake up at a lower level, and steadily (re)build your identity and recall your skills as you learn to cope with the world around you. It could even be a good justification for the leveling-up process applying the way it does.

[Anlashok]

Mindrape and Programmed Amnesia are the closest mechanics in game and neither of them explicitly remove training. Programmed Amnesia does have the option via negative levels, but the normal memory erasure effects don't reduce class levels.

Those are the closest in game mechanics I can think of, still an ask your DM thing though.

[Troacctid]

Pathfinder has a feat (http://www.d20pfsrd.com/feats/story-feats/forgotten-past-story) for amnesiac characters trying to uncover the secrets of their past.