Aquementas

Aquementas is a level 54 water elemental found near Lost Rigger Cove in Tanaris. Aquementas can be summoned by using the Book of Aquor at the Circle of Aquementas. To create the Silver Totem of Aquementas, you may need to defeat Aquamentas. If you summon Aquementas and get killed in the fight, you will still get the totem (note that you don't need an empty inventory as the required items to make the totem will be used up in the process).

Trivia

 * "Aquamentus" is the name of a recurring enemy in the Legend of Zelda series. A green dragon, it appears as a boss of two dungeons in The Legend of Zelda and the boss of the Gnarled Root Dungeon in The Legend of Zelda: Oracle of Seasons.
 * Aqua is the Latin word for water.