Fully restores HP and casts NulAll on a character.
Drains [Fire/Cold/Lightning/Earth] attacks
Tetra Elemental is an item that when used during battle will restore all HP and grant NulFire, NulFrost, NulTide, and NulShock to one target. When 12 are used during Customizing on a piece of armor, it will grant that armor Curseproof. It can be stolen from Master Tonberry or Seymour Natus.
Tetra- is a numerical prefix that refers to four.
Classical elements typically refer to ancient concepts similar to the modern states of matter: earth (solid), water (liquid), air (gas) and fire (plasma). Classical elements are the simplest form of existence, of everything in existence. Many philosophies and worldviews believe in classical elements.