Itzli

Itzli is a new evil witch that appears in Puella Magi Madoka Magica Portable. She is the Witch of Oblivion. It is not part of the regular gameplay, and is only available in the Oblivious barrier, the last of five bonus dungeons provided with the game, unlocked by clearing Homura's route.

The witch of oblivion, with a vengeful nature. A witch who is said to have originally been a magical girl who came from the end of the galaxy. She has shown herself now in order to forget about all the magical girls from this universe.

Trivia

 * Itzli uses shadow magical girls as familiars, identical to those used by Walpurgis Night.
 * Itzli means "obsidian" in the Aztec language.
 * Obsidian was a valuable material prior to the use of iron, like flint, it could be fractured to produce sharp blades or arrowheads. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture. It was also polished to create early mirrors.
 * Obsidian mirrors were used in Aztec shamanic rituals.
 * To Pre-Columbian Mesoamericans, obsidian was a valuable resource that was used extensively in trade, commerce, warfare, and in crafts. Its use of obsidian was extensive and sophisticated; including carved and worked obsidian for tools and decorative objects. Mesoamericans also made a type of sword with obsidian blades mounted in a wooden body. Called a macuahuitl, the weapon was capable of inflicting terrible injuries, combining the sharp cutting edge of an obsidian blade with the ragged cut of a serrated weapon.
 * In Aztec mythology, Itzli (or Itztli) was a god of stone, particularly in the shape of a sacrificial knife. He served Tezcatlipoca as the god of the Second Hour of the Night. He is associated with Chalchiuhtlicue and Tlazolteotl. Itzli was therefore the god of (human) sacrifice and stone knives.
 * Aztec sacrificial knives were not grim instruments of torture as you might imagine. In fact they were adorned with (cute) little faces with wide staring eyes.
 * Upon her death, she launches into the sky like a rocket and explodes.

Speculation

 * Because of the Witch's information, it is suspected that Itzli was a magical girl from another planet, an Alien magical girl.
 * She may have wished to erase magical girls and Incubators from her planet's history.