"The spell is called "Prismatic Spray", not "Taste The Rainbow"." (3.5 Domain, PEACH)

[Pennance]

I started trying to math out how Prismatic Missile is broken, but then found out it isn't. It counts as magic missile, so you will hit with it. Instead of dealing (1d4+1)/2 levels past first, however (with a range of 2-5, average 3, for a total of 15 at level 9) you launch 1missile/3 levels which deal 1d4/1d6/1d8 (average 3; average of 15 at...level 15) or possibly a status effect instead. So, because the stat effects are there and the chance for rolling extra, it's balanced, but otherwise it would actually be mechanically weaker than MM.

Prismatic Grasp is also fine because there are spells at level 1 which deal scaling damage at all so again, mechanically sound, possibly even underpowered.

Well done.