Mom's dismembered leg is called down to deal 300 damage to anything it stomps. It will always stomp on the enemy with the most health. If used in an empty room or during the fight with Mom, it will stomp Isaac instead.
III - The Empress
5.300.4
May your rage bring power
Triggers the Whore of Babylon effect (+1.5 damage, +0.3 speed) for the current room, but without the need for Isaac to have a red heart or less of health.
Teleports Isaac to the Shop. If there is no Shop, this will act as a random teleport. If the Shop has not yet been accessed, this card will unlock the door without requiring a key (as long as the player exits through the main entrance).
Grants the effect of Magic Mushroom (increases all of Isaac's stats except tears), but adds one (temporary) Red Heart container for the current room as opposed to a permanent one.
XII - The Hanged Man
5.300.13
May you find enlightenment
Removes Isaac's body, allowing him to fly around for the duration of the room (same effect as Transcendence).
XIII - Death
5.300.14
Lay waste to all that oppose you
Deals 40 damage to all enemies in the room (same effect as The Necronomicon).
Teleports Isaac to the Treasure Room. If there is no Treasure Room, this will act as a random teleport. Randomly chooses a Treasure Room on Curse of the Labyrinth. If the Treasure Room has not yet been accessed, this card will unlock the door without requiring a key (as long as the player exits through the main entrance). Can also teleport you to the Planetarium
XVIII - The Moon
5.300.19
May you find all you have lost
Teleports the player to the Secret Room. This card will open one random wall once inside the Secret Room, so you can leave even if you don't have any bombs available.
XIX - The Sun
5.300.20
May the light heal and enlighten you
Restores Isaac's full health, deals 100 damage to all enemies in the room, and reveals the map for the current floor, except the Super Secret Room. Removes Curse of Darkness for the current floor.
These cards share the same names as their counterparts (barring the question marks at the end of their names), but have the sprite upside-down, the narrator sound clip reversed, and give different effects.
"Sells" items and pickups in the room for their usual shop price, spawning a matching amount of coins. Does not affect grab bags. If there is nothing to sell, spawns a penny.
Gain Spirit of the Night and +1.5 damage for the current level. Turns Isaac's red hearts into bone hearts, but they revert once the effect ends. Also causes Curse of Darkness that cannot be dispelled.
Doubles your bombs. If you have no bombs, gives you 2 instead.
2 of Diamonds
5.300.24
Always available
Item multiplier
Doubles your coins. If you have no coins, gives you 2 instead.
2 of Spades
5.300.25
Always available
Item multiplier
Doubles your keys. If you have no keys, gives you 2 instead.
2 of Hearts
5.300.26
Always available
Item multiplier
Doubles Isaac's current number of Red Hearts. Does not affect Eternal Hearts, Soul Hearts, or Black Hearts. Doesn't add new Red Heart containers, just fills empty ones.
Clones all pickups and chests in a room (including Shop pickups; the clones can then be picked up for free). Cloned chests will contain exactly the same type of items: if the original contains a pickup, so will the clone; the same is true for collectibles. Cannot clone other Jera runes and trinkets.
Deals 40 damage to all enemies in the room. Consumes all pickups in the room and turns them into Blue Flies and Spiders. Consumes all pedestal items in the room and turns them into random stat upgrades. No effect on shop items.
Rune Shard
5.300.55
Always available
It still glows faintly
Activates a random, weak rune effect: Algiz grants a 3 second shield, Ansuz reveals the map up to 3 rooms away, Berkano gives 1 blue fly and spider, Dagaz gives half a soul heart, Ehwaz makes a trapdoor, Hagalaz destroys some rocks, Jera duplicates one pickup and Perthro rerolls one item.
Soul Stones are all unlocked by beating both Hush and Boss Rush as their respective Tainted character. These are counted in-game as runes and will, as such, drop from items like Rune Bag.
Rerolls the items in the room like The D6, but they cycle back to their original form after one second, repeating. If more uses are stacked, all the rerolls are cycled through.
Invokes Dark Arts, turning Isaac into a phantom that can pass through enemies to paralyze them. After a few seconds, he will attack them all, gaining damage bonuses for each target.
Causes 8 poison farts that leave lingering brown creep, then plants a trail of 7 Butt Bombs in quick succession. Standing on the creep gives +1.35 tears and +1 damage.
Isaac dies, and is immediately revived at half a heart remaining in the same room, with some invincibility time. The soul stone is automatically used upon taking fatal damage, as well, functioning as a minimal extra life.
Spawns The Forgotten as a temporary secondary character, controlled at the same time as Isaac. He dies if his two bone hearts run out, with no further consequence, and disappears when Isaac leaves the room.
Spawns Esau as a temporary secondary character, controlled at the same time as Isaac. He dies if his health runs out, with no further consequence, and disappears when Isaac leaves the room.
These are items other than cards and runes (and pills) that take up the consumable slot. When on the ground, each of these items are uniquely identifiable by their respective icon. These consumables cannot be replicated by either Blank Card or Clear Rune, and Tarot Cloth has no effect on them.
Using the Blank Card with the ? Card teleports the player to the I AM ERROR room of the current floor. This consumes both the Blank Card and the ? Card.
The Empress card's effect can be stacked with multiple uses of the same card (including uses by Blank Card), and also stacks with the Whore of Babylon.
The damage bonus is the number of uses squared, e.g. +1.5 * 4 * 4 damage for using the card via a Blank Card, with Tarot Cloth and Car Battery equipped.
The Devil card's effect does not stack with multiple uses, nor does it stack with The Book of Belial. It also does not increase the chance of a Devil or Angel Room appearing when used like with the Book of Belial.
Blood of the Martyr grants its additional 1.5x damage multiplier with The Devil card.
Using the Joker card in The Womb II or Utero II will instantly teleport the player to the Devil Room or Angel Room with a trapdoor leading to Sheol or to the Cathedral. This can be used to skip Mom's Heart and will not count as a kill.
After unlocking It Lives, Devil or Angel Rooms in The Womb II, Utero II, and Scarred Womb II no longer contain trapdoors and instead have their normal contents.
Using The Joker card can allow Isaac to encounter Devil Rooms or Angel Rooms on floors they otherwise cannot appear on.
If you use the Strength card with only Soul, Black, or Bone Hearts left, and lose the non-Red Hearts while in the same room, you retain the full Red Heart container that Strength grants after you leave.
The foot summoned by The High Priestess can destroy rocks and open doors, including the entrance to Secret Rooms.
The damage dealt by The High Priestess counts as explosion damage, meaning it will not damage Isaac when possessing Host Hat or Pyromaniac.
Using the Strength card as ??? will give you a permanent Soul Heart instead of a temporary one. When Keeper has only one Coin Heart, he can use the Strength card to gain a second one which is also permanent.
While Curse of the Maze is active, The Fool, Moon, Hermit, and Stars cards may fail and leave the player in a different room than intended. The Joker card still works normally.
Using the Temperance card can, in rare cases, spawn the Blood Donation Machine directly on the player, forcing them to use it once. Caution should be taken when using Temperance as The Lost (or when on half a heart of health), as this will instantly kill the player regardless of the Holy Mantle.
All teleportation cards except The Fool are unavailable in Greed Mode.
Rune Shards spawn in place of a Rune that hasn't been unlocked yet. Once all Runes are unlocked, Rune Shards no longer appear.
Leaving Trinkets in a Boss Room or a Treasure Room will transform them into a Cracked Key when on the Ascent back Home.
There is a unique marked skull that will spawn on Depths II or XL. It is marked by a tiny black cross, and when blown up will always drop The Fool card (Or an identified Telepills if Little Baggy has been picked up).
Using Soul of The Lost and then beating a boss for a completion mark within the same room will not count as a completion mark for The Lost. Instead, the completion mark and achievement will go to the character who used the soul stone.
Huge Growth - Increase in size 5 times in a single run. Sources of increased size include "One Makes you Larger" pills, XI - Strength, and Magic Mushroom.
The runes and their names ingame are based on the Elder Futhark alphabet system and its reconstructed Proto-Germanic names. In popular culture, runes often signify that something is in some way magical.
The Suicide King card is a nickname for the King of Hearts, referred to as such because its artwork depicts a king who seems to be sticking a sword into his own head.
The Get out of Jail Free card is a reference to a card with the same name that appears in the table game Monopoly.
The "A Card Against Humanity" card is a reference to the card game Cards Against Humanity.
Ancient Recall, Era Walk, Huge Growth, and Chaos Card are all based on cards from Magic: The Gathering.
The Chaos Card is a reference to the card "Chaos Orb", which also instantly destroys enemies that it touches.
The "Ancient Recall" card is a reference to the card "Ancestral Recall", which also draws three cards.
The "Era Walk" card is a reference to the card "Time Walk", which allows players to take an extra turn.
The "Huge Growth" card is a reference to the card "Giant Growth", which buffs creatures summoned in the game. Its message might be a reference to the card "Become Immense", a card with a similar effect to Giant Growth.
Many cards were given new unique back sprites in Booster Pack #5, some originating from Antibirth.
The "Soul of Cain"'s ability is likely a reference to Red Key being an unlock for Cain in the original Antibirth mod.
The "Soul of Judas" description and ability are a reference to the Spy from Team Fortress 2.
The "Soul of Eve" description and ability refer to how a group of crows is called a murder.
The "Soul of Samson" description is a reference to Judges: it is said that Samson killed an army of 1,000 Philistines using a donkey's jawbone.
The Reverse Tarot Cards refer to tarot card readings, where a reversed card has a different meaning to an upright one.
Typing the command "giveitem k0" into the Debug Console will reveal a secret usable item called "NULL". Executing the command, however, does not give anything.
Hagalaz will open Secret Room doors in L-shaped rooms.
Bug!
Entering a trapdoor created by Ehwaz on Corpse II will result in a black screen. Continuing after this will result in the floor restarting. Completion mark for Mother will not be received even if you have defeated her prior to entering the trapdoor.