Burst:
Frost Reach > Deep Fissure > Volcanic Rune > Frost Reach (swap in an Ulti for the last Frost Reach)
sub in an Ulti for frost reach where it doubles up if you have it. always try to cast your Ulti's fully buffed to get the most out it
Ideally you would have some cover you are using for Line of Sight where you could lay down your ground AOE while buffing and enticing a fight. Upon engaging a group battle lay down the ground AOE and singling out a target while deciding where to take cover. Then you would try to initiate with Frost Reach, then Deep Fissure, Volcanic Rune, and a final Frost Reach to finish the burst. I don't recommend turning while Deep Fissure is going off - it's very hard to aim right. I prep a second before to make sure I can try and predict when my target will be in rage.
Keep alive via LoS and the bird, buffs and heals.
Don't forget that the Netch heals you for no cost when you are out of magicka.
Deep Fissure reaches 20 meters so its longer than Elemental Blockade's 18 meters. Use Elemental Blockade as a reference to how far the Deep Fissure will reach.