Dying/downing to agony while transformed (tonics, boombox, etc.) results in your character having 0 agony resistance after reviving/rallying.
Subsequent deaths or rallies do not restore agony resistance. Unequipping and equipping the items that give AR does restore AR.
Just a small inconvenience when trying to entertain my party members with a boombox before Molten Boss. Needless to say, I wasn’t too helpful in the fight.