We're playing the quest 'Rise of Urthko', where the locked door has 12HP and has 3 shields defense. The heroes must destroy the gate. One of our heroes has Serpent Dagger and wants to apply the poision condition to his target (which in this case is the locked door). I cannot find any information that confirms or debunks if you can apply conditions to a door. Does anyone know that?

If it can be attacked and isn't otherwise immune, it can receive conditions. However, because the door doesn't activate, it won't ever need to test/take damage from the poison.

Thanks for the quick reply Zaltyre