I made this for a request in the NWN General Forum. I know there are a few reaper builds here already, namely Grim Reaper /Bard 4/Fighter 8/PM 28 and The Grim Reaper /Wizard 15/PM 12/WM 13, and perhaps others that don't have the word "reaper" in the build name. The others (that I found) use PM which gives you a nice skeletal arm, but I just don't think the reaper should be raising undead, it would seem more fitting (to me) that he would be intent on sending them to a more final death. As he gains more skill as a sorcerer I would recommend using robes (black casual robe for maximum reaper look) and relying on damage reduction spells rather than ac to stay alive, which means low-magic worlds are a must. I've tried mixing concept and powergaming, hopefully without losing too much of either.
Abilities: Str 14 Dex 12 Con 14 Int 10 Wis 14 -> 16 Cha 14 -> 22
Unbuffed stats: (with normal scythe) HP 372 AC 11 AB 32/27/22/17 Damage 2-8 +9 (critical 19-20 / 4x) Saves: Fortitude 24 Reflex 16 Will 25
With long-lasting buffs* HP 512 AC 23 AB 41/36/31/26 Damage 2-8 +17 (critical 18-20 / 4x) +11-14 fire Saves: Fortitude 26 Reflex 16 Will 25
With medium-lasting buffs** (on top of long-lasting) HP 523 AC 27 AB 48/43/38/33 Damage 2-8 +18 +2 magic (critical 18-20 / 4x) +11-14 fire Saves: Fortitude 29 Reflex 19 Will 28
With short-lasting buffs*** (on top of all above) HP 603 AC 28 AB 54/49/44/39 Damage 2-8 +22 +2 magic +3 bludgeoning +8 divine (critical 18-20 / 4x) +11-14 fire (summed up that makes 48-57) Saves: Fortitude 31 Reflex 20 Will 28
Lastly, you will also have True Strike on top of that.
* Long-lasting buffs are:
Shield
Flame Weapon
Bull's Strength (maxed)
Eagle's Splendor (maxed)
Endurance (maxed)
Keen Edge
Vampiric Touch (maxed)
Greater Magic Weapon
Shadow Shield
Bless
Aid
Magic Vestment
** Medium-lasting buffs are:
Haste
Prayer
Divine Power
Battletide
*** Short-lasting buffs are:
Divine Strength
Battle Mastery
Divine Might
The save DC of his necromancy spells will be reasonably good and 21 levels of sorcerer is usually enough to overcome spell resistance granted by items, but he will often need to rely on his combat abilities. I imagine him using spells mostly for protection, which he is quite good at. With Improved Invisibility and Epic Warding or Premonition up he should do quite well against most opponents.