The Duke coughs out regular Flies and Attack Flies around him and floats around the screen in random directions, while bouncing off of walls. He takes a large amount of knockback from Isaac's tears.
The Duke coughs out regular flies for defense and will keep doing so if you continue destroying them. These flies will circle around him. If he has too many flies around him, he can blow them away at high speeds, which will cause them to follow Isaac.
Once he has sufficient defensive flies, he will proceed to spawn attack flies instead, which are stronger and poised to attack the player from the start.
Actually getting your shots through to him is the most challenging part of this encounter, and that can be accomplished in a few main ways:
- Firing through the gaps in his shield will make it easier to kill him.
- A single Bomb will clear out most of the flies, and deal a very large amount of damage to him.
- The boss gets significantly harder if you can't land your shots right away. The green champion variation is particularly dangerous as shooting down Moters will make it very easy to get hit.
- When the Duke starts spitting up Large Attack Flies, focus on them when they appear to keep things under control.
- If you get swarmed by his Flies, it is always a good idea to leave the Duke alone and concentrate on his spawns. While this will not damage the Duke in any way, ignoring the flies for too long can lead to so many of them that they become too much to handle.
- Having Skatole will grant immunity against all flies that are not orbiting the Duke. Attack flies that have been spawned by the Duke but not yet released from his orbit will harm Isaac if he runs into them.
- The Duke of Flies has three distinct sounds that he uses before an attack. Learning what these are will help when fighting him.
- One sound for spawning Black Flies.
- One sound for spawning Attack Flies.
- One sound for releasing some defensive flies to attack Isaac.
Larger than the original Duke of Flies. Instead of spawning Large Attack Flies, he spawns Suckers.
Shoots blood in all directions when he coughs, and spawns Moters instead of Attack Flies.
- The name "the Duke of Flies" is not a reference to Beelzebub, Edmund was unaware of this connection and simply chose the name because it 'sounded neat' as he stated on tumblr
- The protective ring of insects the Duke spits out to surround himself with is referred to as the Halo Of Flies, just like the item Isaac can pick up to protect himself with orbiting flies.
- The Duke was confirmed to be Edmund McMillen's portrayal of the Pokémon Koffing.
- The stitching below the Duke's mouth appears very similar to an autopsy stitch - a Y-shaped incision that allows access to the cadaver's organs that is then stitched back up when the autopsy is complete.
|Basement||Larry Jr. • Monstro • The Duke of Flies • Gemini • Steven • Famine|
|Cellar||Widow • Pin • The Duke of Flies • Famine • Gurdy Jr. • The Blighted Ovum|
|The Caves||Fistula • Peep • Gurdy • Chub • C.H.A.D. • Pestilence|
|Catacombs||The Husk • The Hollow • The Blighted Ovum • The Carrion Queen • Peep • Pestilence • The Wretched • Gurdy Jr.|
|The Depths||Loki • Monstro II • Gish • War • Mom|
|Necropolis||Mask of Infamy • Daddy Long Legs • The Carrion Queen • The Bloat • Loki • War • The Wretched • Mom|
|The Womb||Scolex • Blastocyst • The Bloat • Death • Conquest • Daddy Long Legs • Triachnid • Teratoma • Mom's Heart • It Lives|
|Utero||Teratoma • The Bloat • Death • Conquest • Daddy Long Legs • Triachnid • Lokii • Mom's Heart • It Lives|
|Sheol||The Fallen • Satan|
|First to fifth and seventh level||The Fallen • Headless Horseman|