Well, I was just browsing this forum today and saw this, and have a quick and dirty solution to a Valen-less party in TOB if you have cheat codes on. CTRL SPACE and CLUAConsole:CreateCreature("valen") works just fine. She arrives a bit low-level for TOB, and for kicks when I did this I jacked her XP using CLUAConsole:SetCurrentXP("InsertMainChar'sXP#"). This had the amusing side-effect of starting a battle with the Vampire Hunters in my Pocket Plane of the Abyss (which is where I was when I created her).
She is incredibly powerful in terms of damage output in the late game, but she also never has too many HPs and is always right smack dab in the monster's face due to her rabid script. This combination can get her dead easily in the later "Improved" battles, particularly on Insane or Hard difficulty settings which I tend to prefer. She is a vampire Cuisinart until then though.