How to Beat Pontiff Sulyvahn?
For melee Pontiff Sulyvahn is quite dangerous and difficult opponent. You need upgrade your weapons, armor and health to win him. Before you get to Sulyvahn, you have to fight with the guards at the entrance. If they almost kill you, then do not even think to go to the Sulyvahn. He will kill you for sure!
The best tactic in this battle is the following: try to remain permanently behind enemy behind him. After his combo of three hits, you can attack him. But do you need it only if he gets to you of these three hits more than once.
In the second phase of the battle you will see phantoms of Pontiff Sulyvahn. Yes, they are much weaker than most boss, but they should not be ignored. Kill the phantoms of the first, and then continue to attack the boss. If you do not, at the moment when you will press the boss, you will approach from behind phantoms and press you.
Pay attention to the moment when Sulyvahn will soar into the air. In this case, the impact should be expected rally, which necessarily need to dodge.
If you play as a magician, or shooter, then wait for the right moment, when you can break the distance, and only then shoot the enemy. Or you can wait until the enemy starts to attack from the air.