Dead Ringer is the Zone 4 boss when playing as Cadence. He appears as a demonic figure wearing a bell on his head and wielding a mallet.
At the top corners of the arena are two sarcoghagi that will spawn Skeletons, Skeleton Mages, Shielded Skeletons, or Mounted Skeletons, which will harass the player during the fight. Destroying the coffins will prevent these enemies from spawning.
Phase 1: Dead Ringer will immediately try to ring all four bells by moving into the square above them and striking them on his next move. At any point, he can get distracted by spotting the player in a cardinal direction, and will charge forward (you can distract him before he rings any bells if you are quick). When charging, he moves once per beat, otherwise he moves once every two beats. He is capable of moving diagonally. During this phase, his bump attack deals two hearts of damage.
If a bell is rung (either by the player or by Dead Ringer), a miniboss will spawn:
- The top-left bell spawns a Green Dragon.
- The top-right bell spawns an Ogre.
- The bottom-left bell spawns a Nightmare.
- The bottom-right bell spawns a Minotaur.
If Dead Ringer charges at the player and crashes into a bell, the bell will be destroyed and will not spawn a miniboss. Bells can also be destroyed with bombs. After a miniboss has been killed, it is possible to summon another by attacking the bell that spawned it.
Bells are treated as though they were immobile crates - they do not count as enemies, and will only be deliberately attacked if the player is standing next to them. However, the bells can be rung unintentionally by striking a nearby enemy with a weapon that can hit multiple targets at once.
Phase 2: Once all four bells have been either rung or destroyed, Dead Ringer will begin to glow yellow and move much faster. All of the bells will disappear (but NOT the enemies or minibosses) and a gong will spawn on the top-center of the field. Dead Ringer moves once each beat, and can move diagonally. If he spots the player in a cardinal direction, he will charge across the screen on his next turn. Dead Ringer's charge now takes him as far as he can possibly move, until he collides with the player (dealing a massive four hearts of damage) or a monster/miniboss (which will immediately be destroyed). The player must trick Dead Ringer into charging into the gong, which will end the fight immediately.
Although unconfirmed, he seems to be damageable the beat he charges if he collides with a monster and gets hit on the same beat. It might be possible to defeat him this way - however, the sheer difficulty of setting up such a strike makes this strategy highly infeasible. Interestingly, though, it is possible to redirect his charge attack with a flail strike, provided Dead Ringer is adjacent to Cadence. This works in both phases.
After his defeat, Dead Ringer will survive the fight, breaking his bell-shaped helmet open, revealing that he is Dorian, Cadence's father, in a sickly and "cursed" state. According to him, he was being controlled by the Necrodancer to fight her against his will. He will then accompany Cadence during her final battle against the Necrodancer. Defeating Dead Ringer unlocks Dorian as a playable character.
A Metal track exists for this boss, even though Aria is unable to fight him without using debug mode or cheats. This is because FamilyJules7x made a Metal version of every song in the game, including songs that would not be heard during an Aria playthrough.