Summoners, we are aware of some issues currently affecting Dungeons, and possibly other parts of the game. We are working to resolve this as soon as possible, and will address the knock ons when we are sure this is all resolved.
Was fighting sp3 bias mephisto with domino, rulk and massacre synergies are there. When landing heavy, he got debuff icon, but wasn't getting any damage from it. Also I'm too lazy to issue a bug for another generic answer, just dropping it here