Will attempt to re-roll monsters into ones with a similar amount of HP.
Re-rolling a monster will replace it with an entirely new one from any floor, making it dangerous to use early on in the game (as Isaac could get monsters from Depths or later).
D10 attempts to reroll monsters into those with similar max HP, making it somewhat safer to use.
The D10 generally will not reroll Bosses but can reroll monsters spawned by bosses.
Using this item can cause some rooms to become impossible to clear. Jumping or flying monsters may become trapped behind rocks after being rerolled, and therefore become unbeatable.
Sealed doors open after 2 minutes, though there are situations that can prevent this failsafe from triggering.
Flying monsters will only be rerolled into other flying monsters, and ground monsters can only be rerolled into ground monsters ( Horfs are classified as ground monsters by the D10).
Some invincible enemies will be rerolled, while others (including most Grimace variants) are completely unaffected.
Using this item in a room with Mom's Hand can be very dangerous, as unless they have already landed, they will be directly on top of Isaac, resulting in the new monsters spawning directly on top of Isaac, instantly dealing contact damage.
Using this item, then exiting the room, such as by teleporting or a bombed door, will cause the enemies to be in their original forms upon Isaac's return.
Book of Virtues: Spawns orange wisps in the middle ring. Tears shot from these wisps have a 10% chance to reroll enemies on hit.
Broken Remote: Using D10 while holding this will first teleport Isaac, and then reroll the enemies in the new room.
3DS The icon of the D10 as seen on the lower 3DS screen.