Kill when he summons 2nd pack of knights to proceed next floor. Killing before that doesn't disable the barrier.
Fighting with Parvin
Tank should stay close to walls by make boss face to him NOT towards to your team any possible ways while they stay behind the boss. Parvin casts frontal 3x wind waves sometimes when hitting and gets huge attack speed buff. Start of fight DPS should avoid using their main skills because parvin will instant vanish and casts single wind waves towards to random players few times, and he comes back to start attacking again. At vanishing phase parvin cast single wind waves total 3 times, also 3x frontal too towards tank. Those frontal might one shot your tank.
Parvin vanish for 3 second, when comes back stays for 7 second later vanishes again.
After that he stop vanishing permanently and knockbacks & silences (5 second) you he does that each 10 second. Also gain ability to reduce your armor by 250/310/370 when hitting on each difficulty. Shockwaves he cast around him damages and reduces move speed by -101
VX Note: After 1st pack you have to burst parvin and keep his low as much possible you can and close your wisp if it is offensive mode.
The moment he summon 2nd pack he gains very huge damage reduction which makes him very hard to kill. That's for sole reason you have to keep him at low HP and kill instant that moment.
That phase he gets temporary buff called Spiked Shield which reflects damage, you can see some kind reddish color around him when he gets that buff. You can either use instant damage skills when buff is not active OR use only auto attack which is %100 safer but takes longer to kill him.
PS: If you are burst him rapidly when buff active he gets very huge heal, obviously you die to reflect also. If you trigger the heal just reset the fight.
Empowered Tower Mode
He summon 4 knights for each summon.
Reduces armor by -430
Shockwaves hurts much more badly & reduces move speed by 500