
It also takes on reddish hue to signify this change. As it takes damage it becomes more aggressive: moving, teleporting, transforming, and attacking at a faster rate. Occasionally, it returns to its main form to perform projectile attacks at a faster pace. Cannot transform into any other Repentance bosses. Can transform into Baby Plum, Bumbino, Reap Creep, and The Pile, but only Baby Plum has a unique sprite. Additionally, many of Hush's attacks do not work properly and the sprite is also unfinished. In order for this to happen, very few bosses must be encountered in the run. It is unable to properly transform into Hush's true form.
Whether it turns into a Champion variant or a regular variant is random and does not depend on which variant was previously defeated. It can rarely transform into two bosses at once. When transforming into certain multi-phase bosses such as Isaac, Delirium copies the phase that that boss would be at, given its current health percentage. When it transforms into a boss, Delirium retains its own health, not the health of the boss it transformed into. Transforms into bosses previously encountered during the run, which can include major bosses such as Mom or It Lives. The projectile size per each attack is random and varies from very small to moderately large. A stray short-range projectile in a random direction. A burst of projectiles that travel outwards in random directions. A spread of 5 projectiles in Isaac's direction. 4 lines of 3 projectiles that spiral outwards. 4 projectiles outwards in a lop-sided cross. 6 projectiles that travel outwards in a zig-zag pattern. 8 slow-moving green-tinted Ipecac projectiles in all directions.
10 projectiles that fluctuate in and out while expanding.14 projectiles that rotate clockwise, counterclockwise, or back and forth while expanding.16 projectiles outwards in all directions.20 projectiles that slowly rotate clockwise or counterclockwise while expanding.Continuously sends out various overlapping patterns of white projectiles for the entire duration of the fight:.Delirium's main form is stationary but teleports erratically around the room and performs the following attacks: