How can I discover the user id knowing only the character name?

Sadly, you can't block people from your games. Only from chatting with you.

If you want to ensure you're playing without them, you basically have to switch to private games, with all of the obvious downside that comes with those. Or switch to a different "kind of game" (e.g. baalrun to split mf or the like) or a different region while they're active and "hunting", seeing how those folks often tend to stick to the same thing for their PKing attempts.

You should be able to type /whois charactername and get their BNet tag. It should work even after they've left your game, at least sometimes (I'm not entirely clear on the why/how/when, there might be a time limit, or maybe I'm imagining/misremembering that it has worked for me?). This is nigh impossible though if their character name includes characters that you can't easily type (like a name in an Asian or cyrillic language, assuming you're not also a speaker of the same language), unless there's a trick to it to make the game autocomplete/suggest character names that I'm not aware of. But as noted by Schnorki, you can't really do much with the BNet tag beyond blocking them from chatting with you (or to add them, which I guess you don't want to do in this case ).

ShadowHeart wrote: 2 years ago

at least sometimes (I'm not entirely clear on the why/how/when, there might be a time limit, or maybe I'm imagining/misremembering that it has worked for me?)

/whois seems to be looking for the last character of that name that you have played with. So generally, it works. However, it seems to also be looking for active characters only so as soon as that character isn't found anymore (e.g. because he went offline or switched characters), it stops working.

Blubbalutsch wrote: 2 years ago

Schnorki wrote: 2 years ago

Sadly, you can't block people from your games. Only from chatting with you.

Just read this and was thinking: God dammit would this be a nice feature blocking ppl from joining ur games. Bit by bit all those slur spammer, Pks, quest destroyer and split farm crasher would be excluded by public consent. Hopefully up to the point where public lists like the spamdomains in my /etc/hosts would emerge i fancy. Just block the sh*t out of them, but the cherry on top would be a non-descriptive message after 3min of door-screen waiting when they try joining a blocked game: "Unable to join game"...make shadowbanning in d2r real!

Aye, it'd be a brilliant feature in just about any game. And yet, noone (that I know of) ever implemented it.

Then again, implementing such game-blocks = happy players whereas not implementing them = happy botters = more money for blizz so...there's your reason as to why it'll never, ever happen.