A green, mutated spider.
Isaac gains four eyes and small fangs, similar to a Trite.
Each shot fires four tears in a narrow spread. Reduces Tears to minimum, but fire rate can still be increased with items and tears up pills.
The Mutant Spider effectively quadruples your damage, so even a player with low damage can achieve high damage output depending on how many tears hit the target.
- The Inner Eye - Mutant Spider overrides The Inner Eye.
- IPECAC - Completely overrides Mutant Spider, nullifying the quad shot effect with no increase to damage.
- Chemical Peel - Has no effect. However, this DOES work on Cain, as he has a 50% chance of a tear having increased damage. Therefore, multiple Mutant Spider tears can have increased damage.
- Mom's Knife - Overrides Mutant Spider with increased charge time and no increase in damage.
- Dr. Fetus - No damage increase, with greatly decreased fire speed.
- Stem Cells - Distorts shot pattern if Stem Cells are acquired first.
- Technology - The laser deals tripled damage, but its fire rate is greatly lowered.
- Technology 2 - The damage of the laser is increased, with the Quad Shot stacking.
- Polyphemus - The damage bonus will be lowered from (damage+4)*2 to a flat +5 per tear.
- Tough Love - More than one tear may be a tooth.
- The Mulligan, Guppy - More attack flies will spawn, due to multiple tears hitting at once.
- The Parasite - In most cases only one tear will split.
- Wiggle Worm - Makes all four tears fire in a waving pattern, which narrows down the spread of Mutant Spider tears.
- Chocolate Milk - All four tears are charged for additional damage.
- Brimstone - Overrides Mutant Spider, with tripled damage and the charge time greatly increased.
- Mom's Eye - Mom's Eye always activates.
- Mutant Spider was changed to be a Special Item in v1.50, a game version available only to The Binding of Isaac: Unholy Edition owners.