Metronome can grant items that haven't been unlocked yet.
Synergies[ | ]
Book of Virtues: If an active item was selected, grants the same wisp as that item. If a passive item was selected, grants any random wisp.
Rock Bottom: Isaac keeps any stat upgrades gained by a random temporary item as long as the item brings his stats over their highest value reached on that run.
Interactions[ | ]
Blanket / Holy Card / Holy Mantle / Wooden Cross: if Metronome is used while the shield is active, any stat changes or familiars/orbitals generated from Metronome will persist between rooms until Metronome is used again or replaced with another active item. Items that modify your stats and have other additional effects will keep the stats but the effect will be gone after leaving the room. For example, the tears down applied from The Inner Eye will persist between rooms, but Isaac will not shoot three tears at once.
Some tear effects from items will remain active between rooms. These include:
Sometimes, these interactions will even occur without a shield item.
Car Battery: Metronome is activated twice at once as expected, but the item chosen for the first activation is shown raised above Isaac's head, instead of the second one that actually remains active.
Moreover, active item effects chosen by Metronome are only activated once.
Bird Cage: Spawns the familiar for the current room, leaving the room it spawned in will only left the sprite over Isaac's head without doing nothing.
Specific Item Effects[ | ]
Certain items used by Metronome have permanent, limited/unusual, or no effect. It is not clear what is intended and what is a bug.
Permanent effects include:
Health, coins, bombs, or keys that are granted to Isaac directly will persist.
D8's rerolled stat multipliers will persist, D4 or D100 will reroll all items permanently and D Infinity mimicking any of the previous also has the same effects.
Damocles will permanently grant the passive version of Damocles.
Genesis will work as normal and will cause Metronome to disappear from the active slot.
Magic Skin will give Isaac a broken heart, spawn an item, and count as an activation of Magic Skin, causing future items to have a chance of being replaced by Magic Skin.
Void absorbing passives and granting stats will persist.
Limited and unusual effects include:
Items do not spawn pickups and consumables that they might when picked up normally.
Items that adjust Isaac's size will not do so.
1up! and Guppy's Collar give no indication of extra lives, but will still work if you die in the room.
Abaddon will not remove red hearts or grant black hearts.
Belly Button and Mom's Purse allow picking up two trinkets in the room, but if another one is picked up outside, one trinket disappears completely along with the extra slot.
Black Candle only adds a black heart and does not remove curses.
Brittle Bones and Divorce Papers do not grant bone hearts. Brittle Bones can still be used to gain permanent tears ups if bone hearts are available.
Crown of Light only adds soul hearts, no damage multiplier.
Dead Cat will only restore one red heart without setting heart containers to 1. It also gives no extra lives.
Deep Pockets allows the picking up of two consumables while in the room and kept outside, but using them will lose the extra slot.
Eden's Blessing will not grant an extra item for the next run.
Little Baggy, Polydactyly, and Starter Deck allow picking up two consumables while in the room and kept outside, but using them will lose the extra slot.
Mega Mush stats increases and Isaac's appearance revert on changing rooms, but Isaac retains the shadow of his large size, the ability to crush rocks, and invulnerability until the 30 seconds are up.
Moving Box will cause items in the room to be packed away into the box until you either find the Moving Box or Metronome gives you the Moving Box effect again.
PHD will not identify pills, but they are still guaranteed to not be negative.
Schoolbag allows picking up two activated items while in the room and they can be kept even outside, but the extra slot and one of the items is lost if another activated item is picked up.
PC It is possible for this item to give an indefinite Breath of Life effect that persists throughout rooms, eventually killing the player.
Bug!
PC If Urn of Souls is activated through Metronome, it won't shoot fire and Isaac could get stuck with the urn in his hands unable to shoot tears. You can fix this by exiting and continuing the run, restarting the room without the urn and without Metronome charges.