Doing the Denova weekly (SM), I had to tank Stormcaller and found he was constantly changing its target.

While fighting on him, its turret simply went left/right during the whole fight, but during the shields/trandoshans phases, many of the plasma arcs landed anywhere, even on a sniper dealing with Calcinis.

I still think something is broken from start with this phase as the shields are supposed to protect from mortar volleys and they only occur at the end of the phase, but I'm unable to understand why Stormcaller changed aggro and dropped plasma arcs on just about anyone all of a sudden following last patch.

We ended up damaging Firebrand to ~5%, then finishing Stormcaller and had to deal with some plasma arcs on Stormcaller itself.

I know of a bug (feature?) involving an insane threat boost when fighting Soa, but it was nothing like that, more of a Zorn's rock throw mechanics taking place on Stormcaller.

Only time I've seen the arc's drop on top of the tanks is when you allow back to back Double Destructions... Doesn't do it all the time but it does seem to be the trigger for when this happens.

Also if the tanks turret is changing targets then the tank is losing aggro..... Make sure the tank that is running around during Defensive mode throws a taunt on Storm Caller before he takes off to make sure its on him or Storm Caller will drop those arc's on someone else and if there under the shield there going to wipe the group.

Only time I've seen the arc's drop on top of the tanks is when you allow back to back Double Destructions... Doesn't do it all the time but it does seem to be the trigger for when this happens.

 

Also if the tanks turret is changing targets then the tank is losing aggro..... Make sure the tank that is running around during Defensive mode throws a taunt on Storm Caller before he takes off to make sure its on him or Storm Caller will drop those arc's on someone else and if there under the shield there going to wipe the group.

If the Stormcaller tank runs out of range of Stormcaller during the shield phase, aggro will move to a DPS or Healer under the shield.

We've also noticed that if the people standing behind Stormcaller stand too close to the middle, they are considered being in front of the tank rather than behind and this will cause the arc to get dropped on them.

The best method we've found to avoid weird things happening is to have 3 dps start off on Firebrand for a few rounds then everyone switch over to Stormcaller.