Longinus

The Longinus also known as Tools that Destroy God are the eighteen top-tier Sacred Gears with enough power to kill Gods.

Summary
This class of Sacred Gears is specifically named after the True Longinus, the first and most powerful, and unlike other Sacred Gear, that has more than one of the same type, the Longinus are utterly and completely unique, and only one of each may exist at a time. Azazel has stated that all Longinus is just a combination of one ability with another. Essentially, they combine powerful abilities that aren’t supposed to be combined.

Out of the thirteen, eleven have appeared in the series thus far (with another one appearing in another series ), but Azazel has mentioned that due to the abnormality on the Sacred Gear system, and the Sacred Gears' ability for growth and change, more Longinus might be born.

Original Longinus
The first 13 Original Longinus made by the God from the Bible.

New Longinus
The 5 new Longinus consisting from the evolution of a Sacred Gear (Aeon Balor) and others currently of unknown origin.

Trivia

 * Four of the thirteen Longinus contain powerful creatures, of which three have had roles in the storyline.
 * The Longinus Canis Lykaon is a reference to the scientific name of the Eastern Timber Wolf (Canis lycaon), a wolf that lives in Eastern Canada. It may also be a reference to Lycaon, the man that was turned into a wolf by Zeus as punishment for feeding him Nyctimus, Lycaon's own son. The form and the backstory in Slash/Dog, however, is similar to the Chinese Tiangou.
 * Out of the eighteen Longinus, four of them are known as the Holy Relics, they are: the Holy Spear - True Longinus, the Holy Grail - Sephiroth Graal the Holy Cross - Incinerate Anthem, and the Holy Nail - Alpheeca Tyrant.
 * During the "Kyoto Incident" in Volume 9, the original Sun Wukong tells Georg that he needs to talk with his Longinus to better grasp its abilities. This suggests that the remaining Longinus that don't have a creature sealed inside them, instead have some other form of consciousness.
 * The name Longinus is based upon the legendary and mystical figure of Christian mythology. Longinus, according to multiple Christian communions, is said to have been the soldier who pierced Jesus' side with a lance.
 * Three of the Four High-Tier Longinus user's have Subspecies Balance Breakers.