This quest is given by Spearhead in the Tenebrous Jungle after you complete the Sunwalker and Stones quest.
He asks you to investigate the ten pillars they are at:
(84, 57, -12), (101, 57, -9), (119, 57, 0), (136, 57, -2), (127, 57, -8), (128, 57, 3), (114, 57, 3), (109, 57, 4), (100, 57, 4), (92, 57, -2).
After this you must kill 6 storm cells, up above the waterfall.
Next up is to found four sacred stones at the bottom of the pond (-12, -134) where the storm cells populate. Picking these up will spawn The Creature of the Black Pond, a level 57-58 heroic ^^ mob.
You do not need to kill him, simply to return to Spearhead for your reward. This also opens up the Mysterious Stones quest.