Quote Originally Posted by QXZ View Post
anyone know what does "Extend Stun" do? I have Nyarlathotep applied the stun extend during the stun phase and it added 2 stacks of stun. but the target immediately recovered after the next turn.
Read the debuff descriptions on the boss. One of them extends the amount of damage the boss takes before Stun wears off, the other the amount of time that a boss takes before the stun wears off.

How good Stun extension is depends on how hard the boss was to Stun. If the boss is easy to Stun, then the extension won't mean shit. On the other hand, bosses which take forever to Stun will be heavily impacted by the extension.