Guppy's Tail

Effects

• Grants a 1/3 chance of replacing Room Clear Awards with a Chest or a Locked Chest, but also a 1/3 chance to replace it with nothing at all.
  • (Added in Afterbirth) The effect does not apply to Coins dropped in Greed Mode.
• This item belongs to the Guppy set. Collecting three items from this set will transform Isaac into Guppy.

Notes

• The drawback to this item is that Keys become much more scarce, while increasing the amount of Locked Chests. This makes taking Guppy's Tail a potential liability early on.
• Due to any found Chests containing items while in (Chest) Chest or (Dark Room) Dark Room, Guppy's Tail can be a good way to quickly stack up more upgrades before facing the final boss.
• This item has no effect in Greed Mode other than counting towards the Guppy Transformation.

Synergies

• (Added in Repentance) Guppy's Eye: Makes key management easier by revealing which Locked Chests are worth opening and which are not.
• (The Left Hand) The Left Hand: Turns all chests into Red Chests, allowing Isaac to get Red Chest items much more quickly. Useful when pursuing the Guppy transformation.
• Mom's Key: Increases the number of drops from Chests and counteracts the increased chance to run into Locked Chests.