This page is meant to show the interactions between a few special items in the game. This page is meant to show, for example, which items you should not take in combination with the few main attack modifiers such as Brimstone, Mom's Knife, Technology, etc.
Note: Most of the item interactions shown here are incorrect. Please read the individual item pages instead.
Each cell in the table shows the resulting effect for the combination of those two items.
|Brimstone overrides Dr. Fetus, does not increase damage||Mom's Knife overrides Brimstone||-||Brimstone overrides Technology.||
If Brimstone was collected first, both shots will fire, but with decreased Brimstone damage.
For Cain, if Brimstone was collected first, Technology 2 will override Brimstone and cause massive damage.
Brimstone will override Technology 2 if Brimstone is taken afterwards. No longer overrides in the latest update.
|Increases damage of Brimstone, but Brimstone charges slower|
Only a bigger blast radius in room where Chocolate Milk is collected (bug)
With Epic Fetus, you will be able to "charge" the shot, meaning you'll have to click twice to cast a missile.
|Mom's Knife overrides Chocolate Milk||Allows partial Brimstone charges, charging before entering a room results in a beam that does no damage. Drastically reduces the overall damage||Increases Technology damage with charge, making laser visually wider||
For Cain - Increases Technology 2 damage. Once you fire the laser, you will not be able to stop firing until you leave the room.
|Adds poison effect to your bombs||Covers the blade in poison||Adds poison effect to Brimstone, but no change in color||Turns Technology laser green and adds poison effect||Technology 2 laser poisons enemies, but no change in color||No effect on Ipecac shots, poison effect stays the same|
|-||Mom's Knife overrides Dr Fetus||Brimstone overrides Dr. Fetus, does not increase damage||Fires both bomb and laser, laser becomes very short, seems to do no damage||Fires both bomb and laser||Severely decreases Dr. Fetus bomb firing speed, does not increase damage|
|Epic Fetus overrides Dr. Fetus||Epic Fetus overrides Mom's Knife after leaving the room||
Epic Fetus overrides Brimstone.
(If Brimstone is acquired first, then while in the room in which Epic Fetus is acquired, Brimstone still fires, and the Epic Fetus cursor is placed on Isaac afterward, and can still be used.)
Adds an invisible laser that does massive damage
Increases time between Epic Fetus shots. Technology 2's laser only fires between Epic Fetus Shots
WIth Cain, Technology 2 overrides Epic Fetus, and Technology 2 damage is increased
|Epic Fetus overrides Ipecac|
|Severely decreases bomb firing speed, does not increase damage||Mom's Knife overrides The Inner Eye||Triples Brimstone damage, but charges 3x slower||Increases Technology damage to maximum, decreases firing rate to minimum|
|Severely decreases bomb firing speed, does not increase damage||
Mom's Knife overrides Mutant Spider
|Quadruples Brimstone damage, but charges 4x slower||Increases Technology damage to maximum, decreases firing rate to minimum||
Does not affect technology 2
Isaac will shoot both tears and laser
|No effect on Ipecac|
|Severely decreases bomb firing speed, does not increase damage||Mom's Knife overrides Ipecac||
Increases damage of Brimstone, but Brimstone charges slower
|Greatly increases Technology damage if Ipecac is picked up after Technology||Both Technology 2 and Ipecac shots are fired||-|
|Applies the freezing effect to Dr. Fetus bombs||
Applies the freezing effect to Mom's Knife
|Applies the freezing effect to Brimstone beam||Applies the freezing effect to Technology laser||Applies the freezing effect to Technology 2 laser||Applies the freezing effect to Ipecac shots|
|Mom's Knife overrides Dr Fetus||-||Mom's Knife overrides Brimstone||Mom's knife overrides Technology||Technology 2 laser fires while charging Mom's Knife, but does no damage||Mom's Knife overrides Ipecac|
|Number One||Turns Mom's Knife yellow||No effect on Brimstone||Turns Technology laser yellow, greatly increases fire rate of laser|
|Dr. Fetus Bombs pass through obstacles||Turns Mom's Knife transparent, knife passes through obstacles||No effect on Brimstone||Destroys objects (poo, flames) instantly||No effect on Technology 2||Does not affect Ipecac - shots will still detonate on obstacles and harm the player. Normal tears caused by having The Parasite will be affected|
|Changes colour of Dr. Fetus bombs and explosions to orange, does not split bombs||Turns Mom's Knife Orange||Technology overrides Parasite, does not split laser||Co-exists with tear shots only||Ipecac shots will split into two normal shots after impact|
|Polyphemus||Severely decreases bomb firing speed, does not increase damage||Adds a huge amount of damage to Mom's Knife||Massive Brimstone damage increase, even one-shotting most bosses, greatly increases charge time||Greatly increases laser width and damage||If Technology 2 is taken first, maximizes the damage of Technology 2||Ipecac projectile flies through enemies and explodes when encountered an obstacle|
|Adds homing effect to Dr. Fetus bombs, decreases bomb firing rate||Turns Mom's Knife white, greatly increases damage and applies slight homing effect||Increases Brimstone damage||Increase size and damage of Technology laser||Adds homing effect to Ipecac shots|
|Adds slowing effect to Dr. Fetus bombs, bombs flash red and yellow||Turns Mom's Knife white, applies slowing effect||Adds slowing effect to Brimstone beam||Adds slowing effect to Technology laser, turns Technology laser white||Adds slowing effect to Technology 2 laser||Adds slowing effect to Ipecac shots|
|Adds homing effect to Dr. Fetus bombs, turns bombs purple||Turns Mom's Knife purple, applies slight homing effect||No effect on Brimstone||Turns Technology laser purple, no homing effect||Adds homing effect to Ipecac shots|
|Mom's Knife overrides Technology||Brimstone overrides Technology.||-||Greatly increases Technology damage if Ipecac is picked up after Technology|
Both shots fire
Mom's Knife overrides Technology 2, laser will still fire but do no damage (bug)
Also reduces knife damage.
|If Brimstone was collected first, both shots will fire, but with decreased Brimstone damageFor Cain, if Brimstone was collected first, Technology 2 will override Brimstone and cause massive damageBrimstone will override Technology 2 if Brimstone is taken afterwards||Both beams fire, allows Technology 2 laser to pass through obstacles if spectral tears are acquired||-||Both Technology 2 and Ipecac shots are fired|
|Mom's Knife wiggles during knife throw, allows multiple hits on enemy during a single throw, does massive damage to larger bosses||No effect on Brimstone||Causes Technology laser to snake, increasing effective width of Technology laser||Does not cause Technology 2 laser to snake, applies wiggle effect to regular tears||Causes Ipecac shot to wiggle, Ipecac is always fire in a straight line while wiggling|