BURN THEM ALL!
Grimtools - Dual wield version
Grimtools - Caster offhand version
There are a lot of pros and cons to both versions of this build but I personally prefer the DW version due to it feeling more like a true Nightblade 
. Here is the outdated 1.2.0.5 Version that due to destroyer prefix having phys res, the offhand version was a bit better âback thenâ.
Idea:
I always wanted to create a build around Vilgazorâs Heart that specifically utilizes all of its conversion. I never could put a competent fire Ring of Steel (RoS) spammer together and going grenado, kinda forces you towards cold damage and the Rimetounge set.
This is something i came up with when i saw the changes made to Mythical Herald of Blazing Ends, hope you enjoy!
Concept / Build idea:
Offense:
This build heavily plays around Burn / Fire Damage on Blackwater Cocktail (BWC) and supplements its damage with completely converted Biting Blades, Vindictive Flame and a lot of Meteors 
. Make sure to get as close to 200 % casting speed as possible.
Defense:
This build is reliant on having high CC resistance and kiting enemies while they burn inside your BWC. Sustain comes from a. Harvest Scythe / Behemoth giving you 2k health regen b. fully converted Bat proc on BWC and c. leech applying to your biting blades
Ingame Stats:
Gear:
Well Emberâs Calling set + Vilgazorâs Heart are mandatory so itâs not a good starter build.
Rings: you can go double Gollus or even take an Mythical Entropic Coil, but I think the Blazing Inferno Ring fits like it was made for this.
Boots: These fix my slow / Stun Res and even trap res, without these capped the build can get pinned down. Take Mythical Wyrmscale Footguards if you want.
Relic: Korvaakâs Deception is the overall better choice but Annihilation also works perfectly fine
The rest i think explains itself.
Devotions:
Viper, Solaelâs Witchbalde: RR
Behemoth, Scythe, Bat: Sustain
Magi, Torch, Phoenix: Dmg
Playstyle:
This build is an SR specialist (maybe also good in Crucible?) Until the Boss room 
. Pull everything together, throw a BWC at your enemies, lay a Thermite Mine below them, throw a Flashbang and go ham on them Biting Blades. These apply Viper RR but only at 50 % potency, for harder enemies you can use Blazing Eruption. Try not to get pinned down and when stuff comes too close, go and reposition. Veil of Shadow in the DW version has insane range, use it to your advantage.
Performance:
Ravager of Souls in 4 min
this is just a proof of concept. All other celestials are also possible but have fun kiting Calla for 10 mins.
SR 75-76 in 7 min
This can be done quicker for sure, but its not the fastest due to being very bad at single target dmg.
SR 80-81 in 8 min
This build is still very safe at SR 80. i didnt try to push higher yet but its definetly possible. Pulling 4 bosses becomes to spooky however.
Closing Statement
This build walks the fine line between Meme and Amazing. While fighting normal SR rooms feels great and is actually quite fast, Bosses feel like a chore. But I feel like this is a very unique touch to the Burn BWC formula, Enjoy!