Number One

Effects

• +1.5 tears.
• (Removed in Repentance) -17.62 range.
• (Added in Repentance) -1.5 range and -20% range multiplier.
• +0.76 tear height.
• Tears turn yellow and are fired from Isaac's lower body rather than his head.

Synergies

• Brimstone / (Added in Repentance) (Tainted Azazel) Tainted Azazel: The laser turns yellow and charges at a much faster rate with no decrease to the range.
• Epic Fetus: Increases fire-rate with no decrease in range. Explosive clouds are now yellow.
• (Added in Afterbirth) Incubus: The Incubus fires at a much faster rate with no decrease to the range.
• Ipecac: Increase fire rate moderately and decreases range only slightly.
• The Ludovico Technique: Turns tear yellow and allows it to be moved much faster.
• Number One: Gives an additional fire rate bonus without further reducing range.
• (Added in Afterbirth †) Pop!: Eyeball tears are yellow, can be fired much quicker, and does not affect their airtime.
• Technology: The laser turns yellow and Technology's firing rate is greatly increased with no decrease to the range.
• (Added in Afterbirth) Tech X: Laser turns yellow, charge time is greatly decreased, and no decrease to the range.
• Tiny Planet: Tears travel roughly the same distance but can be fired much quicker.

Interactions

• (Azazel) Azazel: Lowers range, reduces charge time.
• (Added in Afterbirth †) Compound Fracture / The Parasite: Tears often disappear before being able to split. Split tears also only travel a very short distance.
• Cricket's Body: Tears disappear very quickly after being fired and split tears barely travel at all.
• Dr. Fetus: Not recommended. Makes bombs travel distance very short. The extremely reduced range can turn simple rooms into a challenge and self-damage a constant concern.
• (Added in Afterbirth †) Haemolacria: Does not affect the main tear; however, burst tears travel significantly less far.
• (Added in Afterbirth) Kidney Stone: Number One's range penalty overrides Kidney Stone's. The stone is not affected by short range, otherwise the combo behaves as expected.
• A Lump of Coal: Tears still increase in size and damage as they travel; however, the short-ranged distance limits tear size and damage.
• (Added in Afterbirth) Marked: Tears become orange. The firing rate is increased, Marked's effect is unaffected but the range is reduced.
• Mom's Knife: The knife turns yellow and the maximum range is significantly reduced.
• (Removed in Repentance) Monstro's Lung / (Added in Afterbirth †) Lead Pencil: Not recommended. Tear barrage disappears very close to Isaac.
  • (Added in Repentance) Range is more forgiving.
• (Removed in Repentance) Proptosis: Not recommended. Tears disappear after traveling a very short distance.
  • (Added in Repentance) This is now fixed and works as expected.
• Rubber Cement: Tears often disappear before being able to bounce off walls.
• Toothpicks: Tears become orange.