Best dmg dealer 1 vivi /1 Rogue / 4 Eldritch Archer / 10 Arcane trickster / 4 dragon disciple with composite bow. ( +4 str from mutegen, +4 str disciple + starting str bonus )
Max Dex: Max Chr
Has access to 24 scorching rays daily to imbue the bow.
Scorching ray : You blast your enemies with fiery rays. You may fire one ray, plus one additional ray for every four levels beyond 3rd (to a maximum of three rays at 11th level). Each ray requires a ranged touch attack to hit and deals 4d6 points of fire damage.
and 5 Hellfire ray daily.
Hellfire ray : A blast of hellfire blazes from your hands. You can fire one ray, plus one additional ray for every 4 caster levels beyond 11th (to a maximum of three rays at 19th level). Each ray requires a ranged touch attack to hit and deals 1d6 points of damage per caster level (maximum 15d6)
Each spell fires 3 rays as a free attack from your weapon, each ray applies a 10d6 sneak attack and with a hellfire ray it further splits each ray into two damage types both of which also get a sneak attack.
It is a stupidly broken build.
You can also try the pure caster version with a sorc.
1 vivi / 1 Rogue / 10 Arcane Trickster / 8 Sorc
You lose the extra bow attack + sneak dmg per round but you get more spells per day.
No build unless utilizing sneak attacks and those 2 spells can do half the dmg of these builds.