This build takes the best of both worlds from Emongg's best 2 Sigma builds. The Raid Boss build as everyone does it starts with the qualifier "it only gets good in the late rounds". Instead, this build uses an actually good early round build, then completely switches over to the Raid Boss build once you actually have enough money to make it work. Also let's be real, if you have made it to rounds 5-7, you probably need to switch something up anyways.

Start with the [Trinisphere] build stacking as much damage and weapon speed as possible, then once Round 5 hits, all items are sold and you go pure Raid Boss survivability mode where you end up with more healing than some supports, but you still have the benefit from [Trinisphere] so your damage isn't totally useless.

Lots of rounds are set with optimistic amounts of money being spent; this will still work if you can't afford everything! There are many optional items if need be so don't worry about it too much. For early game [Aerial Distresser] is just icing on the cake, you can go for blues with weapon damage easily; late game [Gloomgauntlet] is amazing but kind of niche, just build to what you can afford. Also, [Zero Gravity] is an option in many rounds simply for when fighting a [Reinhardt] to completely ignore him half the time.