Assassins in Neverwinter Nights are much maligned. Many consider the prestige class weak, ineffective or just superfluous. After all, rogues get backstabs; invisibility and ghostly visage can be cast by arcanists or from scrolls; and the assassinating death attack never manages to paralyse. Or so it would seem. This view of assassin's apparent weakness is compounded by the lack of good builds that use the assassin class. To rectify that, I have created an effective assassin build that I've christened the Shadow Blade.
The Shadow Blade has an unbelievably high AC (If you see the screenshot of my level 27 HotU character, it is 56! (she soloed HotU, hardcore difficulty, of course)) and is thus impossible to hit. Even if the blow supposedly lands, the first does no damage, thanks to Epic Dodge. Even otherwise, 50% of all blows miss anyway, thanks to Self Concealment V. Add in Improved Evasion that makes 50% of all reflex spells miss (or take half damage), we've got ourselves an almost untouchable assassin. Top it up with a 20d6 sneak attack, causing a death attack with a Fortitude save from paralysation of 38, he is, in a word, Murder.
Fading in and out of battle, assassinating the weakest links one by one, while enemy weapons skim air at the place where you appeared and vanished from, the Shadow Blade strikes silent, strikes deep.
The trick to the assassin class is not to have it as a minor class, but as your primary class. You need to do go all the way with an assassin. I sent my SoU Shadow Blade character to one of my friends, and he went through HotU with her. His verdict? "Fun".
So, without further ado, I present The Shadow Blade.