How to beat Bayle the Dread in Elden Ring: Shadow of the Erdtree

Bayle the Dread is easily one of, if not the, hardest boss in Elden Ring: Shadow of the Erdtree. He's optional—which is a red flag if you know FromSoftware games—and the first time you hear about him is from a man with no legs screaming his name over and over out of a relentless thirst for revenge.

As far as dragon bosses go, Bayle is brutal: He may lack arms and a leg after years (centuries?) of conflict, but he's still an agile dragon who can spit lightning storms and set his arena ablaze as you face off against him. You should plan for a lengthy fight, especially if you summon other players to help out (which increases his total HP).

Bayle is located in the Jagged Peak region and you need to fight through a few other dragon bosses before you reach his domain at the top. Once you reach the Jagged Peak Summit site of grace, you can see his arena straight ahead of you. Just make sure you've started Igon's quest before you fight him.

Bayle will drop around 490,000 runes and the Heart of Bayle item which you can take to The Grand Altar of Dragon Communion to trade for either Bayle's Flame Lightning spell or Bayle's Tyranny, an incantation that sets off a fire and lightning AOE around you.

Erdtree map fragments: Uncover the Land of Shadow
Scadutree fragments: How to level up in Erdtree
Erdtree bosses: A full hit list for the DLC
Leda quest: Track the Erdtree main quest
Sir Ansbach quest: Help the former servant of Mohg
Hornsent quest: Complete the quest for vengeance

How to prepare for Bayle the Dread 

• Aim to be around Scadutree Blessing level 15: Bayle is the DLC's Malenia; you want to be as strong as possible before fighting him.
• Don't ignore the Dragon-Hunter's Great Katana: If you found Bayle, chances are you finished the Dragon's Pit dungeon in the southeastern section of Gravesite Plain and earned the great katana that has an "anti-dragon effect". It's absolutely worth upgrading specifically to fight Bayle. Alternatively, weapons that can inflict frostbite are always good for the 20% damage boost you get after it's applied.
• Casters should bring the strongest spells they have: Meteorite of Astel or Ancient Dragons' Lightning Strike do heavy damage to Bayle and can stagger him pretty fast, which is vital if you want to shorten his brutal second phase. Impenetrable Thorns—found near a certain tree boss—is another solid spell to use.
• Prioritize elemental defense: Bayle hits hard with fire and lightning. Consider equipping the Dragoncrest Greatshield and Pearldrake talismans from the base game, and maybe an Opaline Hardtear or the Opaline Bubbletear in your Flask of Wondrous Physick.
• Switch all your flasks to healing: Bayle is such a long fight that you're almost guaranteed to take several hits along the way, so you should invest purely into healing flasks. Your armor and talismans can be used to make up for any FP problems you have. Sorcery and Incantation users can allocate a few flasks to FP, but you still want to come prepared for lots of healing.
• Summon Igon at the start of the fight and your Spirit Ash in the second phase: Igon can hold Bayle's attention long enough for you to deal a ton of damage before the poor old warrior dies. Save your Spirit Ash for when Bayle starts to charge up into his second phase at around two-thirds of his total HP.

Tips for fighting Bayle the Dread

• Target Bayle's head to start and then go for his tail area: Bayle starts out relatively slow compared to his second phase, so you can just focus on hitting his head. Once you're in the second phase, however, fire and lightning AOEs blanket the arena and it's better to just stick close to him and attack the area around his missing leg and tail.
• Try to stagger Bayle as he enters his second phase: Charged attacks and jumping attacks can knock Bayle into a stagger so you can critically attack his glowing eye around the time he would swap to his second phase (two-thirds health). This is a crucial time to chip away his HP so you don't have to survive his chaotic second phase as long.
• Avoid the beam attack by untargeting him with lock-on: When Bayle rises into the sky to shoot his giant beam, untarget him and run in the other direction. The lock-on will only slow you down.
• Pay attention to Bayle's three-hit swipe attack: If the second part of this combo of swipes has him trying to sideways bite you, immediately get in front of him to avoid the third attack where he breathes fire in a horizontal line that goes behind him.
• Dodge Bayle's lightning strike before he lands: When Bayle jumps into the air to drop a lightning strike, you need to dodge out of the way while he's still in the air. Don't try to time it for when he's about to land or you'll get hit.