Don't know if anyone will see or care about this message, but thought I'd chime in and say the "personality" section is quite poorly written for multiple reasons, that I will (briefly) list here:
1) It mentions he only harms or torments people who have given him ""just cause"", but this is completely false. He is shown to torture or kill people on a whim, due to nothing but a very minor annoyance. Instead of merely banishing Vlod, he chooses to torture his spirit to such a degree that it can be felt by the nearby Shani and Geralt, with Shani remarking how uncomfortable she feels during it, despite not even being able to see the spirit.
2) He is described in the game to make deals with many people, and have done so for centuries.'' You also see a victim of someone he's made a deal with in the Blood and Wine expansion, who's shown to be a friendly, compassionate woman. Despite these facts, the wiki page mentions he "only ever seems to make deals with malicious individuals who either are or capable of hurting people for their own ends", which is lazy at best and completely incorrect at worst (it's a mix - he clearly makes deals with, and torments, anyone he wants, as shown in the game).
3) The sentence: "such as Olgierd whom he rightly described as "a degenerate monster" very clearly states the author's opinion on the matter, but presents it as a fact. The whole point of Olgierd actually BEING a "degenerate monster" is that he's become that as the result of WHAT O'DIMM DID TO HIM. So, clear misunderstanding of one of the most important parts about the quest line, on the author's part.
4) The second half of the aforementioned paragraph even concedes to some of these points, but is introduced as facts, not as something that will be contradicted later in the paragraph. Makes for confusing reading.
5) The ending mentions he won't screw over Geralt with tricky side-effects in fulfilling his wishes, but that's not entirely accurate. In one of the rewards, for instance, the saddle turns Roach into a demon.
There probably won't be anyone to read this comment, but he's one of the coolest antagonists in gaming, and I, in my sleep-deprived state, think he deserves a slightly better and more correct bio. Cheers!
PS: No ill-will, at all, is meant to the author of this page. It's generally really good, well-written and covers some good bits. But critiquing the things that could be changed seems more useful.