Seemingly at random during the final boss fight, using a Bell to teleport into the Nightmare Realm will instantly kill both a solo player and a fireteam upon teleporting. Seems to be due to the Nightmare Collapsing debuff never resetting. Have had this bug happen 4 times in two separate instances. First with a fireteam, other three solo. In the second instance, this bug happened twice within a few minutes of one another, and a third time upon leaving to orbit and re-entering the dungeon at the boss checkpoint. Everything appears to work as normal for the first few trips into the Nightmare Realm, but subsequent attempts will randomly not have their timer reset, causing a wipe the instant the teleport happens.