Aspersius

Aspersius is a water elemental located at the Terrace of Endless Spring, it was corrupted by the Burning Legion when they invaded the area. The corrupted water elemental is fought by a party consisting of the Grand Master, Taran Zhu, Taoshi, Hawkmaster Nurong and Fei Li, who vanquish the hostile elemental and claim [Sheilun, Staff of the Mists] from its remains.

Objective of

Drown — Channeled. Floods a portion of the area horizontally for frost damage every 1 second for 10 seconds.
Drifting Away — Trapped in a bubble and floating away! Dispellable. (Used on all party members except the player).
Whirling Maelstrom — Creates a maelstrom of whirling water.
Will also periodically summon a small group of Ooze called Fel Slime.
Random Fel Blast

Aspersius closely resembles Immerseus, with both using the same model, being made from waters of the Vale and existing due to the heavy corruption of those waters.