OK, we tried the weekly heroic and the nightfall. synth_682 and mwilson136 were with me. Synth is a Hunter with the invisibility ability that goes with bladedancer. We tried that strategy of hiding in the 2nd floor alcove (BTW, it's on the LEFT side of the room, so you have to run across the room to get there). Worked like a charm. Once we all got up there, we spent a couple of minutes swapping out weapons to maximize arc damage (Omnigul's shield is Arc, not Solar like most wizards). In the weekly, it took us about 2 minutes and 3 deaths to get him dead. Then we did the Nightfall - less than 45 seconds in, he was toast. Quite literally, we fired a Gjallarhorn and my arc-burn launcher at the same time, switched to icebreaker, and each got off 2 shots, and he was done. Easily the best strategy for this mission. Just do the weekly first, so you get the strategy down before you tackle the nightfall.