Mercurius

Mercurius is a passive item.

Effects

 * Doors stay open after entering a room, even in rooms with enemies, allowing Isaac to leave any time.
 * Increases speed.

Trivia

 * This item's name, its effects and the player's appearance when picked up are references to the Roman God Mercury (known in Latin as Mercurius). Just like Hermes, his equivalent in Greek mythology, Mercury was said to possess a pair of winged sandals which allowed him to move at unimagined speeds.