22 — Prince of Darkness

A demon king's mansion, half tour and half torture: three easy rooms, three incredibly hard ones. Trolly Blogger and Metal Doge debut.

The split is stark — three stages aren't too bad, and three are incredibly hard: endlessly spawning R.Osts backed by the new Trolly Bloggers, a Kory/Rain D./Camelle pile-up, and a three-boss closer in Satan's Bedroom. The wiki calls True Form Normals and Crazed Cats almost essential, and rates the whole thing a clear step past Stairway to Darkness.

The debuts are both attrition tools: Trolly Blogger is a Those Guys-pattern peon with longer range, more speed, and a knockback ability that exists purely to disrupt your front line; Metal Doge is the Metal peon perfected — fast attacks, area damage, 1-damage-per-hit defense — and gets spammed as a shield for stronger enemies from here through the rest of the game.