??? is the boss of The Chest and is the game's final boss in the Wrath of the Lamb expansion. His encounter is very similar to Isaac. Notable differences are that he spawns red flies, and attacks with purple homing tears instead of regular tears. The background music for the fight is the same as the fight with Isaac, My Innermost Apocalypse.
??? will appear lying down in the center of the room, crying on the floor. He shoots radial bursts of tears and some home in on you. Each tear ??? is hit with will cause several retaliatory tears to be fired during the first and second form. ??? also spawns Flies continuously.
Phase 2 begins at 66% health. A light will shine on ???, and he will stand up. ??? will then start shooting purple projectiles, which home slightly, in all directions. He will still retaliate with some tears when hit.
The final phase begins at 33% health. ??? will grow angel wings, begin smiling, and float slightly off the ground. White beams will shoot down from the sky (similarly to the Crack the Sky item), Angelic Babies will join the fight, and ??? will release six homing projectiles at a time in radial bursts. During this phase, ???'s retaliation tears will cease to be fired.
- This boss is a reference to Ending 10, where Isaac finds ??? in the giant chest.
- ??? is technically an alternative version of Isaac (as a boss), having the same attacks only with some variants.
- ??? Is also a reference to BlueBaby, Edmund's Newgrounds name.
- Whenever he is curling up while in his third form, he might turn into Isaac for a single frame.
|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|