Death Mode/Boss AI Changes

Boss	AI changes
King Slime
	The Crown Jewel shoots a spread of three bolts and fires 20% faster. King Slime is three times as large. King Slime jumps farther and falls faster. King Slime takes half as much time to teleport if the player is hidden behind solid tiles, or is at least 20 blocks above him. All Blue, Green, Ice, Purple, Red, and Yellow Slimes are replaced with Spiked Slimes.
Desert Scourge
	Segments are increased from 37 to 42, and size increased by 20% from Normal Mode. Requires two fewer seconds to prepare for its burrow-and-lunge attack. The speed and acceleration boosts from Expert Mode are increased to 133.33% and 125% at maximum respectively. All sand blast projectiles have higher velocity. Shoots 20 sand blasts at the top of its lunge instead of 18. Sand blast spreads increased to 6, 4, and 6 projectiles.
Eye of Cthulhu
	Dashes faster and more often as its health decreases but also performs fewer chain dashes.
Crabulon
	Idles for less time the lower its health, up to two seconds less. Moves even faster as its health decreases.
Eater of Worlds
	Segment count decreased to 69 segments. All segments begin shooting vile spit when 62 segments remain. Head begins shooting cursed flames at 51 segments. Can fly at players who are out of reach easier. It will also get increased acceleration and top speed as it's health decreases. The head segment as well as every other body segment gains 50% DR and double defense.
Brain of Cthulhu
	Can teleport much closer to the player. Creepers move faster. Gains decreased attack delay as its health decreases.
The Hive Mind
	Moves very quickly and teleports extremely often in Phase 2. Can use all attacks upon reaching 53% health.
The Perforators
	All Perforators gain 1, 2, or 3 segments from smallest to largest and a size increase of 10%. All Perforators' enrages are more effective. The Perforator Hive shoots 16 projectiles per volley instead of 14. The Perforator Hive accelerates faster but has a lower maximum speed.
Queen Bee
	Charges have increased speed. Fires stingers extremely rapidly. While enraged, her top speed is increased, and she shoots bees and stingers at an even faster rate.
Skeletron
	Begins the fight and respawns with 4 hands instead of 2. Head and hands have reduced health. Head acceleration increases as health decreases. Hand attacks have much more velocity and quicker acceleration. Fires faster Cursed Skulls at a faster rate. Shoots 5 magic bolts instead of 3 after teleporting.
The Slime God
	Increases acceleration and speed to all slimes, higher as their health decrease. The Slime God fires Unstable Globs at an even higher rate.
Wall of Flesh
	Shoots Death Lasers from the start of the fight Base speed is 75% faster
Queen Slime
	Queen Slime can now perform three or four special attacks after each high leap, instead of just one or two, as well as being more likely to perform three or four than one or two. She will also always perform a teleport before performing her special attacks, and will always attempt to teleport in front of the player depending on their current velocity, teleporting above them if they are not moving or are in the air. Her attacks are overall more aggressive and performed faster in both phases, and tend to have more projectiles per attack.
Cryogen
	Transitions into Phase 2 immediately instead of 85%. Transitions into Phase 3 at 80% health instead of 70%. Transitions into Phase 4 at 60% health instead of 55%. Transitions into Phase 5 at 50% health instead of 45%. Transitions into Phase 6 at 35% health instead of 25%. Transitions into Phase 7 at 25% health instead of 15%. Time to respawn Cryogen's Shield reduced from 12 seconds to 9. Cryogen's Shield is 20% smaller and only has 700 health instead of 1400.
The Twins
	As their health gets lower, the speed and acceleration of the twins increases, and their attack delay is reduced.
Aquatic Scourge
	Number of segments increased from 41 to 51. Amount of segments that can fire projectiles is reduced by 66.67%. Further increased velocity and turn speed, but decreased changes as health lowers. Sand Poison Clouds have lower velocity.
The Destroyer
	The Destroyer's segments are 100% larger, and Probes are 50% larger. Body segments fire lasers at a faster rate. The Destroyer shoots spreads of lasers from its head if the head is facing the player. Top speed, falling speed, and turning speed increase even faster as Destroyer's health lowers. The Destroyer always has maximum aggression during its flying phase. Extra boosts to flying speed and duration of flying attacks now occur at 40% and 20% health. Probes shoot three lasers at once, with staggered velocities.
Brimstone Elemental
	Brimstone Ray now splits into Brimstone Darts that can home into the player. The number of Brimstone Darts from a ring during the cocoon phase is reduced from 16 to 12, but 2 rings are fired at a time instead of 1. Doubled the amount of Brimstone Darts fired in a spread but halved the attack rate and the amount of Hellfireballs fired to transition to the next phase. Number of Brimlings reduced to 1. Brimlings shoot Hellfireballs twice as fast. Reduced the time taken to teleport from 4.63 seconds to 2.63 seconds. Reappears 50% faster after a teleport.
Skeletron Prime
	Fires skulls more frequently when spinning. The head gains a speed boost if gravity is inverted. Hands and head increase in velocity and acceleration as their health decreases.
Calamitas Clone
	The Calamitas Clone can use charge attacks regardless of her HP. The Cataclysmic and Catastrophic Constructs are 20% bigger, their defense is increased from 10 to 15, and their DR is increased from 15% to 22.5%. The Calamitas Clone is 20% smaller, her defense is reduced from 25 to 12, and her DR is reduced from 15% to 7.5%. The Calamitas Clone can randomize her attacks and movement while above 10% health and brothers are not alive. The Calamitas Clone summons 5 more Soul Seekers when she reaches 35% HP. When the Calamitas Clone's health is below 10%, she will begin charging repeatedly until she is defeated, with her charges leaving behind trails of accelerating Brimstone Hellblasts.
Plantera
	Phase 1 Fire rate of seeds is increased. Fires 3 bulbs per cycle when above 75% health, and 4 bulbs when below 75% health. Thorn balls explode after 9 seconds instead of 10. Phase 2 Spawns 10 tentacles at the start of the phase instead of 8. Spawns up to 4 tentacles after charging instead of 2, and the spawn cap for tentacles is increased from 4 to 8 for all tentacles, and from 2 to 4 for attached tentacles. Detached tentacles move faster.
Leviathan and Anahita
	The Leviathan now spawns instantly, and Anahita joins the battle when the Leviathan reaches 70% HP instead of 40%. Anahita and the Leviathan can always use their charge attacks regardless of their current phase. During phase 3, The Leviathan's charges are longer, Anahita's charges are slower, and Anahita only charges 2 times. The Leviathan transitions into Phase 2 immediately instead of at 70% health. The Leviathan transitions into Phase 3 at 70% health instead of 40%. The Leviathan and Anahita transition into Phase 4 at 40% health instead of 20%. Anahita fires 4 Detonating Bubbles at a time instead of 5. Anahita's projectile rings spawn even closer to the player during Phase 4. The Leviathan now performs 1 charge in Phase 2, 2 charges in Phase 2 and 3, and 3 charges in Phase 4. The Leviathan spends less time spawning Aquatic Aberrations, only able to spawn up to 3 per cycle instead of 4. The Leviathan's spawn cap for Aquatic Aberrations is 2 instead of 3. Aquatic Aberrations now push themselves away from each other.
Astrum Aureus
	Now damages itself for 1% of its health to summon Aureus Spawns, up to a minimum of 1 remaining health. Increased velocity and spread of Astral Flame Crystals. Aureus Spawns charge at the player for 10 seconds instead of 5 before exploding. Aureus Spawns can fire homing Astral Flame Crystals every 3 seconds while not charging. Aureus Spawns can now move away from other Aureus Spawns.
Golem
	Golem jumps much further and more rapidly. The Golem Head in phase 2 fires lasers more rapidly. The Golem Body fires four lasers regardless of health in phase 3. The Golem Head fires lingering fireballs regardless of health in phase 3.
The Plaguebringer Goliath
	Fires more rockets and charges at higher speeds. Gains increased top speed and spawns minions and shoots missiles at a higher rate.
Empress of Light
	Switches between attacks faster, sometimes allowing them to overlap. Increased movement speed. Ethereal Lance V3 is far more common, and more commonly has 4 walls. Prismatic Shards V2 spreads out much quicker and further. Empress's "charging" animation, which has no attack associated with it, is far less common. All attacks have more projectiles and last longer than in Revengeance.
Duke Fishron
	Increased dash displacement. Minimap icon disappears during phase 3. When below 20% health, charges endlessly at the player. All projectiles have increased velocity.
Ravager
	The Ravager's jumps gain even more speed as its life decreases. The Ravager's claws are always launched at maximum speed. Flame Pillars fire blue flames more quickly, firing a total of 5 flames before despawning instead of 3. The speed of the red bolts fired by the head after it's broken is doubled.
Lunatic Cultist
	Projectiles travel faster Ancient dooms explode faster Moves faster while relocating
Astrum Deus
	Segment size increased again. Number of segments increased from 71 to 81 before splitting, and from 36 to 41 after splitting. Movement speed and rate of fire are further increased. Can fly at any time before splitting, and only leaves mines instead of firing lasers while flying regardless of health. When one split worm is killed, instead of dying, the other one will survive and become enraged. The enraged worm will become translucent, no longer changes color to signify behavior changes, and has access to all of its attacks at all times. Only the last worm killed will drop loot and count as a defeat. The enraged worm's body and tail segments have 25 defense and 15% DR, whereas its head has 12 defense and 7.5% DR.
Moon Lord
	Clots heal for 1,500 instead of 1,250. All projectiles have their velocity increased. The Moon Lord and True Eyes of Cthulhu are more aggressive.
Profaned Guardians
	All Profaned Guardians and Profaned Rocks move faster and take shorter time to perform attacks. Holy Bombs, Holy Fire, Molten Blasts, and Profaned Spears move faster. Guardian Healer fires 16 Holy Crystal Shards instead of 14. Holy Crystal Shards have twice as much random spread. Healing stars no longer spawn. Profaned Rocks cover a greater area around the Guardian Defender. Profaned Rocks are distanced away from each other and no longer have even formations. Guardian Commander and Guardian Defender swap sides more often.
Dragonfolly
	Enters Phase 3 at 40% life. Increased speed and aggression.
Providence, the Profaned Goddess
	Providence has a new, different attack pattern which is significantly more difficult and harder to predict. She has decreased attack delay as her HP decreases. She will no longer summon Cocoon Healing Stars while hiding in her cocoon. The crystal will disappear after 35 seconds instead of a minute.
Storm Weaver
	Segments are increased from 51 to 61 and size increased by 5%. Charges 5% more frequently. Rains two additional Frost Waves with 7% less spacing than in Classic Mode.
Ceaseless Void
	Each formation of Dark Energy now has 6/7/8/9 arms and 20/23/26/29 Dark Energies.
Signus, Envoy of the Devourer
	Signus is generally more aggressive and cycles through phases faster as its health decreases.
Polterghast
	Transitions into Phase 2 (Necroghast) at 90% health instead of 80%. Transitions into Phase 3 (Necroplasm) at 60% health instead of 50%. Moves much faster at 25% health instead of 10% health. Phantoms Spirits shoot at an even higher frequency. Gains velocity and acceleration as HP decreases. Can hook increased distances as HP decreases. Hooks fire faster and more often as HP decreases.
The Old Duke
	Switches between its attacks even faster and has further increased movement speed. Charges are even faster in velocity and occur even more frequently.
The Devourer of Gods
	The sky no longer changes colors to indicate the phases and stays pitch black for the entire fight. The Devourer of Gods always moves at maximum speed, regardless of health. During the final phase: The Devourer of Gods shoots Fireballs at a higher rate. The Devourer of Gods changes more often between the passive and aggressive phases.
Yharon, Dragon of Rebirth
	Yharon has decreased delays between attacks. Most of Yharon's slow charges are replaced with fast charges. Yharon spawns in subphase 2, and in subphase 5 after Phase 2 begins. Yharon transitions into subphase 3 at 80% health. Yharon transitions into subphase 6 at 35.8% health and subphase 7 at 16.5% health. Yharon launches more fireballs during his second phase. Summons more Infernadoes in place of Flarenadoes.
Exo Mechs
	Ares: Further increased projectile velocity of all four weapons. Tesla Cannon, Plasma Cannon, and Gauss Nuke become even more predictive. Tesla Spheres connect from an even further distance. Gauss Nuke tracks the player more closely. Exo Overload Beams are telegraphed for less time. Artemis/Apollo: Both of them have faster attacks, more predictiveness, and take less time to perform special attacks. Increased the number of lasers fired by Artemis during the Laser Shotgun Barrage attack, and it rotates the Exothermal Beam more. Apollo's rockets have greater homing speed and stronger anti-clump push. Thanatos: Moves faster, slow down at a closer distance to the player, can have more segments open at once, takes less damage from open segments, and fires lasers with greater predictiveness. Increased the number of lasers resulting from the Gamma Disintegration Beam.
Supreme Witch, Calamitas
	Brimstone Fireblasts and Gigablasts explode into 16 and 36 Brimstone Darts respectively. Cataclysm and Catastrophe fire 16 Brimstone Darts per burst. The arena created by Supreme Witch, Calamitas is now 127x127 (inner available area is 125x125) blocks.