You're about 18 months late on this.

The combo used to be using ranged mines to proc convergence that would pull everyone into a corner up against a wall where the mines could all trigger dealing huge damage to 1 person (likely getting the kill) and follow it up with a negate and streak to prevent them from escaping or casting heals.

Unfortunately in U35, they gutted the [snip] out of mines and magsorc bomber hasn't been the same since. It still works ok when its part of a group because you can negate proc convergence into streak to lock down enemies for the group to finish off, but outside of that, you will likely want to stick with a traditional NB Tether or DK cleave bomber.

If you're dead-set on still using sorc for this, I'd practice destro ulti/negate/mines into pulsar + fury.

Each of the first 3 skills (destro ult, negate or mines) is what you use to proc dark convergence (this will typically be on the back bar), then you switch to the front bar, cast streak into 1 or 2 fury on squishy looking targets then spam pulsar or maybe frags to try and get 1 kill to proc vicious death to hopefully cause a chain reaction that would wipe the group.