How do I make a 9th level Gunslinger into a Pale Stranger? Is it as simple as adding a couple feats and AC bumps to the Pale Stranger?
Is it as simple as adding a couple feats and AC bumps to the Pale Stranger?
No, as a Pale Stranger is an Undead monster and therefore quite a different creature from a normal Gunslinger.
If you're looking for mechanics, I'd start with the Pale Stranger and add some features making it identifiable as a rizen version of the dead Gunslinger. If it's a story element you're looking for, you'll have to ask yourself how the Gunslinger died and what unfinished business keeps it from its final rest.
Well go pale stranger, then add ability score modifiers +4+4+2+2+0-2 to chosen ability scores (this is described in the advancing monsters with class levels section of the beastiary), then add 9 class levels.