OP was indeed right, that was mentioned in a veeery old video. Quite sure it's been scrapped though (sadly)
I am pretty sure that in one of newer videos they said that there is no resurrection in the game. I mean half of the last stream they had were trying to get more res scrolls for partie members which died and they did not had any res scrolls in inventory or no gold to buy some. Though I guess mayyyybe in arenas they left resurrection although I am also verrry skeptical about whole mp arena and have 0 interest in it.
Personally I'm very skeptical when it comes to the competitive aspect of the multi-player version. In Larian's co-op highlight videos they frequently emphasise how you can straight up kill your party members.
I think that they said that you can do quests that does not have same goals as your ones and that you can disagree with other player (you need to kill person x, other player needs to protect person x) and they had to click special option "make war" before they started fighting so I guess there would not be sneak attacks
I guess you can still plant em poisoned healing potions or some grenades set to explode though.