The Block Devil attacks by making some of the blocks from the floors and walls come together, forming his body. The blocks used for this are identifiable prior to moving by their lavender color, as the immobile blocks are purple. The eye then comes from below the screen to enter into the blocks and shoots plasma balls. After this the blocks go back to their original spots in the walls and floor. The eye appears below the floor and makes all the blocks that were used attack by jumping out of their spots, and thus restart its attack pattern. The higher the difficulty setting, the faster the Block Devil will go through this pattern.
The Block Devil is weak to the Rebound Striker, though the Thunder Wool is also effective at dealing damage. The Triple Blade's downward-shooting ability while Mega Man, Proto Man, or Bass is jumping, the Wheel Cutter (if timed correctly) and the Screw Crusher (from Special Stage 2, as Mega Man) can be used to hit the eye when it appears on the bottom of the screen, out of reach of other weapons.
- This boss' attack methods are very similar to the attack methods of the Picopico-kun's from Mega Man 2, as both involve making the blocks in the stage background suddenly fly out of their areas and try to ram into Mega Man. Also like the Picopico-kun, the areas where the blocks originally were have transparent ones behind them, though this only goes for the blocks on the ceiling and walls for the Block Devil.
- As its name would suggest, Block Devil is the least liquid-like of all the devil-type bosses.
- While fighting Block Devil on the Easy difficulty setting, one can stand on the entire floor since the blocks vacated by Block Devil's pieces remain solid, unlike Normal and Hard modes where one can fall through the floor and die.
- The Block Devil appears with other Devil robots in the Short Circuits for Issue 55 of the Archie Comics Mega Man series.
|The "Devil" series robots|
| Yellow Devil • Yellow Devil MK-II • Yellow Devil MK-III • Black Yellow Devil • New Yellow Devil|
Green Devil • Twin Devil • Petit Devil Yellow • Petit Devil Green • Block Devil • Dark Moon • Grey Devil
Shadow Devil • Rainbow Devil • Lava Demon • "Steel Devil" • Chaos Devil