Backstory: I'm relatively new to 3.5, I've really only played a handful of sessions. However, I feel like I have a fairly decent grasp on the rules. I was speaking to a group of my friends about observing them play in part of their epic campaign, as I have never really seen anything about level 8 or so. They agreed and offered to let me even role-play one of the side characters for the session. My understanding is he is a henchmen/cohort-esque type of character who probably isn't always around.
All I know is he is a rogue 3/ninja 3/chameleon 10 and that *he has a homebrewed feat that allows him to apply touch spells to his ranged bow attacks*. My understanding is that they are about to encounter 3 very highpowered multiclass fullcasters like Ur priest/sublime chord/etc (basically the DM likes to make super cheesy characters for the PCs to encounter). Unfortunately, I'll also be like 10 levels* (errata'd: 2 levels) under anyone else, but I'd like to remain relatively useful without getting in the way or being detrimental to the party.
I'm not entirely sure about what other feats/stats/items he has, but I imagine I will have a little bit of ability to alter them. Along with the floating chameleon feat and other chameleon abilities I have some flexibility as to how to play the character. What I'm thinking at this point is going with combat/divine foci and putting zen archery as his bonus feat along with the +6 ability score (hoping he has a decent wisdom score already, otherwise why ninja?).
I believe what I'm hoping you guys can help me with is:
A) What spells would be useful to prepare (Shouldn't be anything aside from PHB, PHB II, SC). I have access to all divine spells, however. I've been trying to find spells that have no SR, no save. So far: Splinterbolt, Spiritjaws, Evard's Black Tentacles.
B) What should my strategy be going into it? I'm afraid that even bothering to attack the super high level casters will just be meaningless. Should I focus on buffing the rest of the party? killing adds/summons? Other ideas? I was considering dust of sneezing and choking, but I doubt it'd be allowed.
C) Is this the most efficient approach to rogue/ninja/chameleon or is there something I'm overlooking?
D) Any other advice.