Stage I
Lorian, the elder prince, is the one who fights you first. He’s a large warrior. Lacking mobility on his own, he’ll teleport to unleash his most dangerous strikes. Dodging his normal attacks isn’t too hard, but when he glows white, you have to quickly see where he’s teleporting and figure out when to dodge his returning strike. It’s very tricky.
Stay up close with this boss, and get your attacks in after each of his swings. Although his major strikes are fairly dangerous, he doesn’t do a good job of retaliating, which lets you score heavy damage throughout the encounter.
Fire Resistance is good, but Magic Resistance is also important (or it will be in just a moment).
Stage II
Don’t celebrate when you take Lorian down. His brother resurrects him and then gets onto Lorian’s back. That can’t bode well.
The second stage is very similar in terms of Lorian’s tactics, but Lothric adds ranged magical damage to the fight. This starts something like a race, as the two combined are almost guaranteed to get damage on you. Can you kill them before your Estus Flasks run out?
For this reason, you have to attack very aggressively whenever you get a proper dodge and can hit Lorian. Side and rear attacks are the best because they’ll deal damage to both twins. As soon as Lorian falls, Lothric collapses and tries to resurrect him again, but this time, you’re free to cut the weaker brother in half. As long as you landed some damage against Lothric during this phase, you should be able to kill him before he succeeds.
If you’re comfortable with this idea, try doing the fight without locking on to Lorian. His teleports really make life hard when you’re locked on. Controlling the camera directly can be easier in the long run because you don’t get as distracted when he disappears. Try things both ways, and see which one suits your playstyle.
After the fight, get the Bonfire. If you want, you can read through Archdragon Peak to go after that optional area. Or, proceed to the write-up for Kiln of the First Flame. You can end the game here and now!