The Ether Monster, a huge, red-scaled brute, appeared only once, in Ultima VII inside the Tetrahedron Generator. It is unknown from where exactly the Guardian got this monster, but it is very strong and tough, can slay even a level-8 Avatar in a matter of seconds. Also its skin is very tough, giving it high resistance values. A Glass Sword or the Black Sword are the easier ways to kill it without cheating, as most other weapons simply won't do it. However, other powerful weapons, such as the Triple Crossbow in combination with Magic Bolts, can work well.