Rift Quest:The Battle for Ember Isle  

If you go up the path you took to fight the Ember Lord, then cross that ledge and go down the other side, the down the switchback, you will come to the fissure.

There is an even smaller tunnel inside that leads to the inner chamber. Click on the Volcanic Fissure to overload it. Karris will appear with two Malgems, but Solya appears and holds the Malgems while you place the Crest of Bahralt on the small platform by clicking it. This stops the Malgems and makes Karris much weaker. Before you can kill him, though, he declares he will release Maelforge even if he has to sacrifice every one of his followers, and he vanishes.