Sharp Plug

Sharp Plug is a passive item.

Effects

 * If Isaac's current activated item has no charges, attempting to activate the item fully recharges it in exchange for two hearts of Isaac's health.
 * If the item has any charges, the Sharp Plug will not work.

Synergies

 * Blank Card: Grants infinite health when combined with XIX - The Sun. Other cards such as V - The Hierophant and VI - The Lovers result in no net loss of health and can be used to trigger items that activate upon taking damage.
 * Cancer: Repeated uses within the same room cost only half a heart.
 * The Gamekid: If Isaac has red heart containers, killing four enemies negates the health cost, and killing more results in a net gain of health.
 * Pyromaniac: Isaac can regenerate the lost health with bombs, essentially allowing 2 bombs to be converted to a full item recharge.
 * Pyromaniac + Ipecac/Dr. Fetus/Epic Fetus: If Isaac has enough heart containers, the explosions can be used to heal him, granting infinite item recharges.
 * Scapular: At half a heart, Isaac will gain a soul heart. As long as Isaac has a red heart container, the soul heart will absorb Sharp Plug's damage, causing the Scapular to trigger again as long as it has not already triggered in the current room.
 * The Wafer: Reduces the health cost to half a heart.
 * The Wafer + Book of Revelations: Grants unlimited soul hearts.
 * The Wafer + The Gamekid: If Isaac has red heart containers, only one enemy needs to be killed to negate the health cost.
 * The Wafer + The Nail: Grants unlimited soul hearts.
 * The Wafer + Prayer Card: Two uses produces a filled heart container, allowing a player to max out their heart containers at no net cost of hearts.
 * The Wafer + Satanic Bible: Grants unlimited black hearts.
 * The Wafer + Yum Heart: Allows for unlimited regeneration of red hearts.

Interactions

 * 9 Volt: Renders the Sharp Plug unusable. Sharp Plug can only be used if the item is at 0 charge, but 9 Volt instantly gives 1 charge to the item upon activation.
 * Breath Of Life: When the charge for Breath Of Life reaches zero, the Sharp Plug will immediately take effect if the player continues to hold the Use Item button, dealing 2 hearts of damage.
 * Holy Mantle: Holy Mantle blocks the damage from Sharp Plug if the shield is active, but also keeps Isaac's active item from charging. Using Sharp Plug again in the same room will cause it to function normally.
 * Isaac's Heart: Renders the Sharp Plug unusable.

Seed
BKXE 1ZBZ (First floor shop, The Wafer and A Quarter in an urn in first floor treasure room)