Update 8/25/2023: I finally bit the bullet and aura forma'd her aura slot and re-forma'd the previously mismatched polarity in the bottom right, so this build is officially no longer janked! You don't have to do any of that yourself, though. [Corrosive Projection] is a nice aura, in my opinion, because it works well in higher levels and makes it easier to run certain armor strip subsumes; however, the original pick of [Steel Charge] will still hold up for you if you're budget!

NOTE: Fire Blast isn't needed, nor is it the best subsume! As mentioned below, I picked this for flavor - performance-wise it's held back by the 75% armor strip cap (93% total with this aura). If you want to really optimize, try a strip like Tharros Strike (will 100% strip at this strength or even lower, easy to spam) or a straight damage boost, or even a utility like Nourish (particularly helpful if you have no Energize on your build). You can also run this with no subsume at all!

NOTE 2: Why did I use an aura forma? Build flexibility: this allows me to put my triple umbral Warcry facetank build on the next mod loadout slot over. Not necessary if you aren't interested in using the specific minmaxed Warcry facetank variant I have on the same [Valkyr Prime] (or in generally having a bunch of different builds on a single copy of Valk). If you ARE interested, go ahead and check out https://overframe.gg/build/122443/ for that build.

NOTE 3: See https://overframe.gg/build/122441/ for the accompanying Valkyr Talons build.

NOTE 4: See https://overframe.gg/build/560638/ if you want to read about tweaking this build slightly for endurance disruption purposes, including level cap slide attack one-shot capability (the main difference is really just the [Talons], if you're curious).

NOTE 5: But Guanshiyin, you used TWO Umbral forma on [Valkyr] here! One on the Warframe, one on her [Talons]! What are you doing?! Very stupid things. Look, if you aren't batshit crazy and dedicated to [Valkyr] (and specifically to her [Talons]) despite her not being meta, this build probably isn't for you. Go play [Protea] or someone else similarly respectable and powerful and useful. This [Valkyr]'s for if you wanna stick your head in the sand and play as the screamy catwife and use Hysteria as much as humanly possible, no matter the cost.

Credit to --Aegis--Grey for suggesting improvements to my initial version of this build and yielding the current version of it!

Strategy

Very simple unga bunga strategy for the convenience of very simple Valkyr-loving gremlins like myself. Enter mission. Activate Hysteria. Activate Warcry. Swing away.

As far as subsumes go: I like Fire Blast for the flavor, mostly, but Tharros Strike is a better armor strip to use (no stupid 75% cap, reaches 100% strip in one cast with relatively little ability strength). Other picks include Nourish if you want energy economy and forced viral on [Talons]; Eclipse if you want a straightforward damage boost; and various forms of grouping if you are interested in making your melee life a little more convenient, though grouping isn't going to be the most ideal with this particular stat spread. (I do use grouping at times via Vazarin on this build too, so that's an option if you don't want to subsume grouping on. See below for more!)

If you subsume Fire Blast onto her 3 like I did here, tap it anytime you meet an enemy you can't one-shot with her Talons' slide attack (Corrupted Heavy Bombards on the Steel Path come to mind). One cast, two at best, should be enough to one-shot these as well. Plus, it's thematically and aesthetically fitting (and brings back some of the sense of the old knockdown on heavy attack in previous iterations of Valkyr's Talons, for nostalgia's sake). Even with negative range, it's enough to function as a really high-range heavy attack, which is okay because you should only ever need to use it on one or two targets at a time (everything else, like I said, should already be one-shot by [Talons] without Fire Blast in regular play if you follow my build or similar).

I recommend that you tap aim every little while during Hysteria (and immediately melee afterwards to return to immortality), just in case things go topsy-turvy and you're left with several tens of thousands to take on a measly 300 HP from your Hysteria self-damage counter when you unwillingly are forced out of Hysteria, due to whatever unfortunate circumstances you might encounter. (Only applicable in really high levels like Steel Path survival. Not a problem in normal star chart missions, where all the damage you can possibly take is just peanuts anyway.)

I have a decent melee weapon on this loadout so that if I ever need something other than Hysteria and Valkyr Talons, I have it. I pair with Vazarin for a cover-my-ass button (thanks, Protective Dash!) if I ever have to de-cast and re-cast (i.e. if I fuck up and touch a disgusting Nullifier bubble by accident, or if, Void forbid, one of those horrid Ancient Disruptors lives long enough to steal my energy). Vazarin's grouping (ability 2 from this Focus school) is also really lovely for this melee playstyle. This is super flexible as far as Focus schools go, however: Naramon is a relevant option thanks to its synergy with upkeeping your Gladiator stacks from your triple Gladiator statstick (I strongly recommend doing this on your loadout's standard melee!); Madurai is Madurai; and Unairu will free up that armor subsume slot if you have Caustic Strike unlocked. The one school I wouldn't use here is actually Zenurik, since Wellspring won't give you any energy while you're channeling an ability - which is, ideally, 100% of the time if you're using this build.

Venka (Prime) is nice, but not necessary, to give you that Walmart-brand Hysteria when forced out of Hysteria. Be sure to equip as many Gladiator mods as you own (three maximum) on your melee of choice to lend [Valkyr]'s [Talons] a whopping bonus 330% critical chance when at full combo!

Stats breakdown

High duration and maxed efficiency should be self-evident with a duration-based buff like Warcry plus a high-drain channeled ability like Hysteria. Same goes for maxing her energy with Primed Flow. Combined with the all-important Arcane Energize, this allows [Valkyr] to pretty comfortably keep up Hysteria consistently without any other support, as long as she's getting kills. (Getting constant kills also contributes to [Eternal War], which is further serviced by that high duration.) Efficiency affects channeling drain more than duration, hence why I prioritized it over duration. (Note that even without [Streamline] or maxed [Fleeting Expertise], and given the duration I use, this build minimizes Hysteria's energy drain, which is the ultimate goal here.)

High strength is pretty no-brainer as well: I just went for as much as possible. (No strict need to use [Umbral Intensify] if you just want viable results here, but I did because fuck it, YOLO.) This leaves range as your dump stat. Despite the minimal range of this build, Ripline actually functions pretty well (it has high base range, after all) and Fire Blast works well enough for my applications (at least up to level 1,000 in Steel Path, you can handily solo clear mobs without armor strip and only need stripping for heavy units). Feel free to adjust as needed if you prefer higher range.

No survivability mods because if you play this correctly you'll never leave Hysteria and thus will never need to worry about taking any damage whatsoever. (Yes, this means the only point of Warcry is to buff the attack speed of her Talons.)

Arcane Fury is the melee Arcane of choice rather than Strike because high-strength Warcry plus [Berserker Fury] on [Talons] already boosts her attack speed to near the cap (or at least to the peak of what I as a human can handle playing). Feel free to use Molt Augmented or Molt [Vigor] if you want extra Warcry speed plus damage output.

Preparation is used so you always start with enough energy to last a whole mission, including short, low-density speedruns where you may not be generating and consuming many energy orbs. Left this mod two ranks below max for mod capacity drain optimization, and because this fills the entire energy bar anyway, so maxing it gives no further benefits.

Miscellany: I use two crimson shards to boost ability strength (because I LOVE my Warcry speed boost, considering I use [Talons]' own combos to move around, so a melee speed boost is basically also a movement speed boost); two violet shards to boost melee critical damage (this build fulfills the energy requirement to double that base critical damage boost from each shard!); and one blue shard to boost energy capacity, all Tauforged (only the best for my baby). However, shards are up to taste, and this is by no means the optimal setup or the one you'll like most. As mentioned above, remember to stack Gladiator mods on your regular melee for 330% extra critical chance on [Talons] at full combo. Finally, I like to use a [Panzer Vulpaphyla] with [Tenacious Bond] for even more critical damage (and because of the way Panzer's larval form works, this is guaranteed to have 100% uptime, even if your pet goes down!) and free passive viral proccing in a wide range - all the standard stuff for Panzers.

Where can (or should) I use this build?

So the elephant in the room: stupid build, right? The answer is yes. This is only if you want to play Hysteria all day, every day. It shows that you CAN do this if you WANT to do so. It does NOT show that this is meta or optimal or even recommended in general, because even I, a diehard Hysteria fan, do not necessarily recommend this in general. This build cannot defend objectives, provide good CC (Fire Blast's range is so limited), [Protect] mission objectives, heal your squad, give good damage boosts (again, range is limited, so unless your teammate(s) love melee and stick to you like white on rice when you originally cast Warcry...), or even deal the best DPS. There are honestly much better ways of surviving than "hurr durr press 4 to become invincible" (because that self-damage counter will really get ya if you run into a Nullifier or similar and you haven't been aim-tapping religiously, or sometimes, even if you have been).

So where CAN you use this build? Personally, I like to head to Steel Path Circulus in solo mode, put on some music, and just mindlessly slice away. I did a solo three-hour Steel Path Void survival mission this way without deaths or problems. Yes, you can achieve a high enough kills-per-second rate to do this as a solo player. Again, it's not optimal, but you CAN do it if you want to.

This build will also typically do you just fine in exterminate missions, several assassination missions (weirdly, I have consistently killed Steel Path Vay [Hek] with this build), and any objective defense mission where you don't need to bring something that can actually heal or shield the objective itself, but then again, like, any Warframe with half a build can do that, so that doesn't mean anything. Not for Eidolons (obviously). Not really for disruptions because her damage doesn't scale so well without a 100% strip option and a primer (I have a build for that and will try to post it soon!). Also, the Talons do not scale well in general at high levels thanks to being raw-damage, low-status, non-forced-bleed weapons, even with armor strip. Not for Arbitrations because yeah, drones flick off Exalted weapon damage like fleas from a horse.

You're insane.

Yep!