DoorBuild and Guide

The purpose of Door is not to deal damage at all, but more so to literally die. Let me explain, if you examine both of his skills, you'll notice that they are all straightforward abilities that simply deal damage with no additional effects. As a 2-star unit, you already know that his damage won't scale well into the late game. However, when you take a closer look at his passive ability, and especially his ultimate, you'll immediately see what Door's true purpose is. Door's ultimate, “To The Universe In the Alley,” provides a mass buff that grants 2 Moxie to all allies, shields every ally, and even applies [Inspire] for 2 rounds, allowing allies to start the round with +1 Moxie.

Additionally, his passive, “Modesty,” grants everyone a single Moxie upon his death. This lets his allies use their ultimates very fast. Yes, he does die after using his ultimate. Still, this shouldn't be seen as a disadvantage at all, as Door is relatively weak while on the field, and it's much better to remove him and let someone from the back row take his place. This can be particularly useful in planned setup plays, where you intend to sacrifice Door and already have a back row replacement prepared. Door’s ultimate can actually be used twice if you have Necrologist on the team, her ultimate will save an ally from lethal DMG, meaning Door can live after using his ultimate once.