The demon drake Valac. This boss is a twin-headed demon dragon that seems less like a dragon and more a draconic centipede with its mouth running all the wall down its underside to the tail! More Teeth than the Osmond Family does not begin to describe this thing!
Once you start Stage 8, a huge swarm of glass shards rips through the room, tearing parts of the stage apart. As you progress through it, it continues destroying parts of the stage, and chases you at several points. All this, combined with the absolutely frantic music, screams one thing; Zangetsu has the attention of the castle's master. And she is PISSED.
If you fail to protect Alfred as he's preparing a spell to stop corrupted Zangetsu, Zangetsu uses his massive scythe to instantly mow down his three former allies. In his euphoria of killing the interlopers, he transforms into a skeletal demon laughing maniacally in a black and red silhouetted scene.
And worse: Miriam's health doesn't deplete UNTIL he transforms. The implication is that they only died after seeing the outcome of their failure.
Stage 6 and the boss Bloodless in general. As you wander through the stage, you're treated to many 8-bit style scenes of cages, iron maidens hung from the ceilings and blood all around, which gives way to Bloodless's scene. You walk into her taking a bath in her blood, which she proceeds to spring out of with a Noblewoman's Laugh. All of her attacks are blood related, and on the first time she uses her Bloody Storm attack, it will not only hurt you if you're not under a parasol she makes, but also covers the entire BACKGROUND in blood. One has to only wonder: where did she get so much BLOOD!?
Curse of the Moon 2
The very first boss of the game, the drago-Symbiote. Granted dragons can be pretty intimidating but this one ups the creep factor by 1, having a long tail that ends in a smiling creature that fires electrical beams and 2, having a corpse inside its normal mouth that fires off the fire breath!
And just before you enter the boss room you can see the dragon's silhouette sitting on a distant perch watching you like a bird of prey before literally diving into the fight.
The stage 6 fight Titankhamun. The boss of the museum stage is, of course, one of the exhibits. Said exhibit being a towering sarcophagus with some unseen horror trying to break out! Only the entire time you are fighting the sarcophagus itself and the final attack will certainly creep out anyone with a phobia of insects. When the final blow is struck, the hands of a mummy break through the face but you never see the mummy but you do have a massive wave of scarabs burst out of the sarcophagus in a desperation attack! Afterward, you see a mass of skulls is resting inside and the hands just stay where they are. Almost as if the scarabs were the ones controlling it...
This even leaves its mark on Episode 2 EX's intermission screen between stages 6 and 7. The scene is largely Played for Laughs for the amusement of the gaming community, but take a second to look at the scenario from the point of view of the characters.
The final level of the game. Just like the initial finale of the first game, there is a major hazard pestering you courtesy of the tower's master. Before it was wave after wave of glass shards trying to eviscerate our heroes. Now it is swarms of killer insects controlled by the boss Abaddon! Eventually, it comes to a point where Abaddon himself chases you while surrounded by their insects!
And speaking of Abaddon, their design in the second phase. Abaddon becomes this enormous insect with six arms, oddly placed eyes along their body, and exposed organs!
Mephisto, the final boss of Episode 2. His design is certainly not an appealing one in the slightest. And for bonus points? Mephisto is Ritual of the Night's save room. Let's repeat that: the save room is, of all things, the Final Boss.
Sariel, full stop! This is the true final boss and it has what could possibly be the most nightmare-inducing design in the entire franchise! First off there's the entrance to their domain on the moon. As our heroes make their way towards them they pass by a number of giant rabbit skeletons and enter the final arena. Sariel initially has no face which would be creepy enough but then a gaping hole appears with blood dripping out! They have clearly seen better days as their whole body is cracked up and are wearing chains, their wings are smiling crescent moons, and they are accompanied by two more of the rabbits acting as living tentacles. Overall, Sariel can only be described as a more demented version of Gremory. In fact, between their design, attacks, and location, it could be a pretty safe bet that this unholy abomination is Gremory's real superior!