So what the hell is heart of selig and doombringer used for? I'm playing with a couple of buddies and we're doing a bunch of mythic runs and I keep getting them.
I switched to Selig build by both using new gear coming in, rerolling a few items, and having a second neck, fully rolled well in cube. I had a ton of the mats for reforging rerolls (reroll every item until it became a star) and decent amount of neck transfigure tokens to get good second aspect on 3 of 4 different necks. Still, I rarely locked items with transfiguration, so I could switch builds and fill in items if needed.
After playing it for 3 or 4 hours, I didn't find the full Selig build better than the traditional WW with Grandfather and Starless Skies, in that shit would one shot me more using Selig. It's possible I was doing something wrong or mixed up some key aspect, I guess, so YMMV.