Diablo 3 Walkthrough: Act 3, Bastion's Keep to Azmodan

Part 3 of our Diablo 3 walkthrough covers Act 3, the war act. It starts at Bastion's Keep, the fortress under siege in the north, and ends deep in the Arreat Crater with the fight against Azmodan, Lord of Sin. It is the shortest act in quests, but it has four boss fights.

Diablo 3 walkthrough: ← Previous part  |  Next part →

The whole walkthrough

Quests in Act 3

1. The Siege of Bastion's Keep
2. Turning the Tide
3. The Breached Keep
4. Tremors in the Stone
5. Machines of War
6. Siegebreaker
7. Heart of Sin

1. The Siege of Bastion's Keep

You arrive at the Bastion's Keep Watchtower. The keep is under attack by Azmodan's army.

1. Talk to Tyrael to take the quest.
2. Go into the Bastion's Keep Stronghold and up to the Skycrown Battlements.
3. Light the five signal beacons along the walls. There is only one real path, so just follow it and light each one as you pass.
4. Find Sergeant Dalen at the end of the battlements.

2. Turning the Tide

Demons hold the walls, and the keep's catapults are down.

1. Talk to Sergeant Dalen to start.
2. Move into Stonefort. It is a long, zig-zag level with few side paths.
3. Raise the three catapults. At each one, defend the soldiers while they set it up. Stand near them and kill anything that runs at them.

3. The Breached Keep: Ghom

Demons are getting in from somewhere below.

1. Talk to Tyrael in the Stronghold.
2. Go down into The Keep Depths, Levels 1, 2 and 3.
3. At the end of Level 3, enter The Larder. Ghom is waiting.

Boss: Ghom, Lord of Gluttony. A simple fight with one rule: stay out of the green stuff.

• He drops clouds of poison gas that hurt every second you stand in them. They last a while, so the room slowly fills up.
• He also spews acid in a cone in front of him. Don't stand right in front of his face for long.
• Kite him around the room in a big circle so you are always walking into clean air. Fight near the edge of the gas, never inside it.

Portal back to the Stronghold when he's down.

4. Tremors in the Stone

A very short quest. Tyrael is gone from the Stronghold, so talk to Lieutenant Lavail. Strange noises are coming from the Armory.

1. Go to the Armory. Something is wrong with Leah and the soulstone.
2. Kill the demon spawn that appear. They are weak.
3. Talk to Leah.

5. Machines of War

1. Go back to the Stronghold, then out to the Arreat Gate, where Tyrael joins you.
2. Cross the Bridge of Korsikk into the Fields of Slaughter.
3. The demons have big siege weapons here. Find and destroy them. The area is packed with demons, so move from one machine to the next and don't chase every pack.

6. Siegebreaker

1. Meet Tyrael at Rakkis Crossing, a very long bridge. There is a waypoint in the middle.
2. Fight across to the Edge of the Abyss. There is no waypoint at the end, so don't leave halfway.
3. The Siegebreaker Assault Beast attacks.

Boss: the Siegebreaker Assault Beast. A huge melee brute.

• His ground pound hits the area around him and knocks you back. He can do it more than once in a row.
• Melee heroes: hit him, then step out when he winds up. Ranged heroes: keep your distance and keep moving.
• Burst damage works well here. Save your big cooldowns for when he is busy with your follower.

7. Heart of Sin: Cydaea and Azmodan

Now you go down into the crater where Azmodan's army is coming from.

1. Go through Arreat Crater Level 1 into the Tower of the Damned, Levels 1 and 2.
2. In the Heart of the Damned, kill the Daughters of Pain and destroy the first Sin Heart.
3. Go to Arreat Crater Level 2 and into the Tower of the Cursed, Levels 1 and 2.
4. In the Heart of the Cursed, fight Cydaea, Maiden of Lust, then destroy the second Sin Heart.
5. Take the stairs down to The Core of Arreat and walk to the end. That is the Heart of Sin, where Azmodan waits.

Boss: Cydaea. She fights with spiders, webs that hold you, and ranged bolts. Kill the spiders fast, step out of webs, and keep hitting her between waves.

Boss: Azmodan, Lord of Sin. The act boss is big and slow but has a lot of area attacks.

• Fireballs: he throws large fireballs that slowly follow you and leave a pool of fire. Walk away from them, then away from the pool.
• Falling corpses: when he channels a big circle on the ground, corpses rain down inside it. Run out of the circle.
• Fire beam: a long ray of fire that reaches far. Move sideways out of its line.
• Demon gates: portals appear and let his servants in. Kill minions only when there are too many, otherwise keep the pressure on Azmodan.

Be patient. Hit him between his big attacks and never stand still. When he falls, his soul goes into the Black Soulstone and you head back to the keep. Act 4 starts from there: the High Heavens.

We may earn a commission from links on this page.

Love the world? The Book of Tyrael covers the angels, demons and heroes of Diablo III.

Tips for this part

• Don't leave Rakkis Crossing halfway. There is no waypoint at the Siegebreaker, and walking the bridge twice is no fun.
• Kill the Sin Hearts' guards first. Daughters of Pain and other demons in the heart rooms do real damage.
• Bring a ranged or movement skill. Ghom, Siegebreaker and Azmodan all reward you for keeping your distance.
• Visit the Stronghold vendors. Act 3 is a good time to reroll or craft a better weapon.

My take

Act 3 is my favourite act in the base game. The keep battle feels like a real war and the pace never drops. Ghom is the one boss I always underestimate. Which Act 3 boss gave you the most trouble?

FAQ

How many quests are in Act 3?

Seven: The Siege of Bastion's Keep, Turning the Tide, The Breached Keep, Tremors in the Stone, Machines of War, Siegebreaker and Heart of Sin. It is the act with the fewest quests.

What level should I be for Azmodan?

There is no set level, because monsters scale to you. If Azmodan feels too strong, lower the difficulty or focus on gear with more toughness and life.

Where is Ghom in Diablo 3?

In The Larder at the end of The Keep Depths Level 3, during The Breached Keep quest.

Where is Kanai's Cube?

Kanai's Cube is not part of the story. It is in the Ruins of Sescheron, an Act 3 zone you reach in Adventure Mode. It is worth getting once you finish the campaign.

Diablo 3 walkthrough: ← Previous part  |  Next part →