Some notes about being an "evolved" build
Apart from what it looks like, I did not just copy that build. Thing is I started this build trying to make Enchant Weapon a main damage dealer with Conflagrate, but when I reached empowered monos the build was not working well so I switched to a Flame Reave build. By the time I looked for a guide I already had most of the build done, and by coincidence, I had reached a very similar build as Wootles. But that guide helped me with some ideas, mostly about enchant weapon auto-cast, the use of a scepter, and other minor things.
The difference is that, besides building differently in many points, I also tried to push the build as far as it could go, and proved that you can run EVERY content with it. I lost interest in keeping pushing before the build could not progress, so maybe someone can push it even further. Also, just like Wootles, I'm by no means a LE expert, so I believe someone may still make an ultimate version of this build.
PS: You will see that some sections of the guide, and the build itself is very similar to Wootle's, this is because the builds are really very similar and there's no escape from some interactions with the skills and passives. Please do check his guide, and give credit to him.
How far can this build go?
This build is all content-able, but with some observations.
You can comfortably do 250 corruption, and t3 dungeons and arena without having the whole build set.
With the whole set, you can do 400+ corruption echoes without much hassle. But to kill 400+ Orobyss and echoes bosses, t4 arena and Dungeon bosses, you will need to play the build with attention and with not much space for errors
Why the Sceptre?
This idea came from Wootles guide, thing is that there's a node in the Flame Reave tree, Arcane Severance 4/4, that grants base spell damage as additional fire damage, it's a direct conversion with 4 points invested. This makes the scepter provide strong base damage for the build, and considering that we still get space for a sword offhand, this outweighs any two-handers that we could use. All of this while also getting more attack speed, so it's a worthwhile investment.
Why Gemini instead of Off-hand or Shield?
Because of attack speed, damage and armor shred. The bonus you get from the sword can't be given by shields or catalysts. Also, defense is already good with all the ward generation we get from the build.
Why not use Jasper's Searing Pride?
There's a third version of this build in YT that uses this item, but I consider that build to not be as strong, and in the video they run very low corruption to showcase it. I have tried the weapon myself, and 0LP one so, I might be wrong. But the increases in skill levels do not pay off the losing of raw damage from both weapons. But the worse part is the attack speed issue, you would be hitting much more slowly, and if you hit slowly you 1) Take longer to build stacks, and 2) Gain much less ward per hit. So I believe the version of Flame Reave build that uses this item needs more work, or maybe even an update to the weapon to really shine here.