We're very, very sorry.
Dark Souls 3 boss: how to beat Pontiff Sulyvahn
Pontiff Sulyvahn is not an easy fight. This will be a stumbling block for many players.
The Pontiff wields two enormous swords. One deals fire damage, and he tends to use it in sweeping attacks. The other does magic damage, and is generally used for thrust. You’ll want armour that can protect you from both damage types, if possible, and a shield to match. This is a battle that really changes if you alter your build appropriately; slow and heavy tanks may benefit from a little holiday in something more agile.
The Pontiff fights like most of his knight buddies outside, but dialled up to 11. You could probably tough it out if things didn’t get worse in the second stage, when the Pontiff not only gains the ability to summon a phantom to aid him and distract you, but begins to indulge himself flapping about on wings, in order to unleash dive attacks.
One tactic that works well in the first stage, and to a lesser degree in the second, is to keep your distance so that the Pontiff rushes towards you. If you're not too heavily equipped, this attack is fairly easily dodged by rolling forward and to the left or right. You can paddle the Pontiff once or twice, depending on the speed of your weapon and stamina reserves, then sprint to the opposite end of the arena. With any luck, he'll repeat the same attack. If not, get to the other end of the arena and try again. It takes a while, but it's doable.
In the second stage you'll need to be more conservative with when you attack and when you just sprint away and try again, in order to ensure the phantom doesn't foil your plan. You can try beating up the phantom, but it just comes back, and it's usually easier to avoid it if you can get both figures doing the same attacks.
In general though, this is just really not a good time; apart from kitting yourself out in appropriate armour, there’s little you can do besides duel with finesse.
Well, you can summon, too – and this is a popular spot for it. There’s an NPC summon outside, Black Hand Gotthard, whom you should bring in at least once, because he gives you the By My Sword emote, which is rad. An extra body makes all the difference in this fight. Bring a friend. Bring two friends. Sulyvahn cannot cope with multiple targets and will regularly leave his bottom exposed for a paddling.
When he’s down, you’ll receive the Soul of Pontiff Sulyvahn and can activate the Pontiff Sulyvahn bonfire. This is a good time to head hack to the hub; Greirat will return to Firelink Shrine if you have completed Siegward’s quest so far, and Yuria will have something interesting to tell you if you've been chasing the third ending.
You’re tempted by that door beyond the Pontiff’s bonfire, but we’ll come to that. For now, we have other places to explore.