Sharp Plug

Sharp Plug is a passive item.

Effects

 * Damages Isaac in exchange for fully recharging Isaac's current activated item.
 * Sharp Plug costs two hearts of health to use.
 * Sharp Plug's heart cost is one half-heart per charge slot filled. The health cost is not increased in later stages where half-heart damage is upgraded to full heart.
 * If the item has any charges, the Sharp Plug will not work.

Synergies

 * Damage-triggered items: Each half heart used up by activating Sharp Plug triggers damage effects separately, allowing multiple payouts.
 * The Keeper takes only one heart of damage.
 * Expends health for charges at the rate of 2 charges per 1 Coin Heart. If an item is 1-charge, removes 1 Coin Heart.
 * : As long as Isaac has more than 2 full hearts or  1.5 hearts, time can be rewinded indefinitely since the health used to recharge the item is refunded upon use.
 * : The active item in the main slot is fully charged as normal and the secondary slot gains as many charges as the main one did.
 * : Reduces the health cost to half a heart (except for Keeper).
 * Tainted Magdalene's can be used infinitely, allowing for infinite invincibility frames from taking damage. Paired with Tainted Magdalene's melee attack, this can easily win a run.

Interactions

 * : Renders the Sharp Plug unusable. Sharp Plug can only be used if the item is at 0 charges, but 9 Volt instantly gives 1 charge to the item upon activation.
 * As Sharp Plug can now be used with charges and the cost is based on charges filled, 9 Volt now synergizes with Sharp Plug, lowering the cost of using it by half a heart on 2+ charge items.
 * : Expends up to 6 full hearts if possible with no charges given.
 * : Attempting to recharge the Eraser with the Sharp Plug fails and only hurts Isaac for half a heart.
 * : Holy Mantle blocks the damage from Sharp Plug if the shield is active, but also keeps Isaac's active item from charging.
 * Bypasses the Holy Mantle and gives charges as usual.
 * : Renders the Sharp Plug unusable.
 * : No benefit from this item unless he has a respawn item because his active item's charge will not refill if the effect activates. Sharp Plug only activates upon receiving actual damage.
 * No effect, as The Lost doesn't have health.
 * When turned into The Lost via the white fire, activating Sharp Plug will take the health cost from the original character's health. will not block the health cost.
 * : Sharp Plug will not work with Mega Blast.
 * Works as intended, giving 1 charge per half a heart.
 * / : Soul/blood charges are used before Sharp Plug when available.

Seeds
BKXE 1ZBZ (First floor Shop; The Wafer and A Quarter in an urn in first-floor treasure room) D1JR VDCR (First floor Shop; Secret Room with coins is left of spawn; second floor Treasure Room contains The Wafer.)