Sar'this

Sar'this can be found in Terokkar Forest. It seems that he has a pact with Illidari Lord Balthas where he gave him his blood, but still seems to owe him a favour. Maybe due to this he's called a heretic.

The Soul Cannon
During the quest, the character talks to Sar'this and gets its help to obtain the Flawless Arcane Essence.

Soul Cannon Cut Scene

 * say
 * emote
 * say

''Sar'this walks around the edge of Lake Jorune to cardinal compass points. At each stop, an elemental is summoned.''

''At this station, an Air elemental is summoned. You slay it.''
 * say
 * say

''A water elemental is summoned. You slay it.''
 * say

Sar'this continues on around the lake.
 * say

''An earth elemental is summoned. You slay this as well.''
 * say

Sar'this continues around the lake.
 * say

''A fire elemental is summoned. Again, you slay it.''
 * say

Again, Sar'this moves on.
 * say

Flawless Arcane Elemental is summoned.
 * say
 * say

You slay the elemental and retrieve the Flawless Arcane Essence.