I'm the kind of person who would like to try out every subrace at least once, so I'm often looking for builds to modify for less-used subbies. One step is to search the open-subrace forum for the subrace in question. As mentioned, it's much easier to modify an open-subrace build up to secret or UR, than to modify a BUR down to secret or UR. And many builds list possible subraces to step up to, or people (like me will post questions or comments for their own attempts at modifying the builds.
When searching for "prismatic", I got two results:
Looking Forward There are many UR and BUR subraces which would be of benefit to this build, though they will also require some re-tooling of the ability points especially. Even some secret ones could fit nicely. Keep your eye out for the following...
. . .
My Top HC's 57 - Fenia Witc-HC-raftbane (Ploder) - Clr57 43 - Stirling the Fort-HC-oming (Uni Tank) - Pal43 43 - Phorik Bus-HC-raft (Zen) - Rgr43 40 - Peisinoe the Myt-HC-hanter (Bard) - Brd39/Pal1 40 - Malina Lhûg As-HC-law (DSM!) - BDD21/Sor19 40 - Vernus the Dra-HC-onian (Tank) - GDD35/Blk6/Brd4
no compromises is Subrace: "PT - Air Genasi" its difficult for me to say if prismatic would fit his build.
That's actually a really good question, one which probably doesn't get addressed enough -- you could post a question directly on the build or do it here.
At a quick glance, the starting stats after subby are:
str - 16 dex - 16 con - 14 Int - 10 Wis - 12 Cha - 8
For Prismatic, I would suggest Str - 14 (16 after subby) Dex -16 (14 after subby) Con - 12 (12 after subby) Int - 12 (11 after subby) Wis - 14 (14 after subby) Cha - 8 (10 after subby)
You're giving up a little Con, but will get it back with your xDD levels (i believe it's +2 with 15 levels)
You'll also lose a little Dex (-2), which may be unavoidable with due to Prismatic subby -- it's feasible that you could find a Dex Artifact to make up the difference, but, imho, high Dex on a Str build is more luxury than necessity.