I don't see any of the Block Damage or Unkillable toons, so your best bet is gonna be a tanky CA Team.

I would focus on Ninja (Damage & Dec Def), Valkyrie (Shields & CA), Brago (Dec Atk, Inc Def & secondary Damage), Duchess (Block Debuffs & Speed Aura), and your last spot could go a number of different ways.  

If you can get this team to a 3:2 or 4:3 speed tune, you should be able to keep Block Debuffs up to counter the stun. If not, you may need to use Achorite as your fifth for Buff Extension.

If you can get it tuned without Buff Extension, then you can put in more damage:  

• Frozen Bansee & Occult Brawler are great poisoners, and they are already built, but Venomage is quite a bit better than either of them because of the A1 poison activation, and she offers another source for Dec Atk & Dec Def.   
• If you need an Inc Speed buff, Razelvarg may be the answer
• Wisper is another strong DPS option, and she brings Weaken, but she gets extra turns that might be a problem 
• You coud also use Geomancer for Weaken & Damage.   

If you can stack enough Defense on Valk, you won't need Lifesteal gear with big shields out of Valk (esp if you have an Inc Def buff up before she places the shields each time) and the damage mitigation from Duchess. Otherwise, you will want your DPS toons in Lifesteal.  

If you don't end up needing Duchess (esp if you don't want to regear her), you might find Sepulcher to be right for the Block Debuffs spot and she also offers Dec Atk & Inc Def.     

Warmaster (or Giant Slayer for multi-hitters) is a must for dedicated Demon Lord toons, and works well with Lifesteal gear.  Warmaster procs off of the Counterattacks is the secret sauce that makes CA so powerful for the this sort of team.  Also, any mastery that alters turn meter will throw off a speed tuned team.   

Are you familiar with Deadwood Jedi?  His site has a tremendous amount of information on speed-tuning, including a calculator that allows you to enter your stats and see when your buffs & debuffs pop up and fall off.  There are a tremendous number of specific speed tunes on the site.

If you can get to the higher speeds, Valk's passive should not screw you up. I ran a fast Valk CA team for a very long time.  If you don't think you have the gear to swing a 3:2 or 4:3 team, this is a link to a straightforward 1:1 CA team with Valkyrie that has speeds that will maintian the turn order agaisnt all affinities even with Valk's passive proccing:

https://deadwoodjedi.com/speed-tunes/affinity-friendly-valkyrie/

Good Luck.  

^ That has to be a scam/malicious link right?

Also to OP: You've got a great roster and you're almost there BUT right now UNM is gonna be rough. Wiley gave the right advice. My suggestion tho is to get Mikage as soon as possible.

Without doing speed tunes and whatnot, you can probably brute-force a 2 Key UNM once you have Mikage. You've got Duchess which is huge for damage reduction between her passive and the Veil buff.

Mikage, Ninja, Duchess, Whisper and Ultimate Death Knight or Iron Brago, but personally I'd go with UDK first to see. There's a decent amount of damage mitigation with both IB and UDK but UDK also has the Shield + heal with sometimes redirecting the Stun to himself.

There might be an issue using Geomancer and Ninja, because Geomancer's passive is somewhat based on the HP Burn being his and not anyone else's so Ninja might reduce it and then replace it with his own.

But yeah, till you get Mikage, you've gotten the best advice already I think

Another thing to mention about using Brago is the value of his Passive in Demon Lord.  He boosts your full team Defense by 10% of his own, so if you can get him to 5K (or more), you are granting tremendous survivabilty to your DPS toons and are making Valk's shields even bigger.

IMO, a traditional Demon Lord CA Team is one of the strongest use-cases for Iron Brago.

That's a great comment/response, thanks a bunch @WileyMan.

Only thing is one of my clans higher ranked players recommends not using Ninja for CB because in order to get him to work well there you need him to have a certain speed, which makes him too slow to progress you through other content, so basically save him for other content because he's that good that you need him geared differently than for the Demon Lord.

I do know about Deadwood Jedi and actually flicked through every single tune he has up and simply don't have the champions, I didn't realize the empty slots were basically customizable 😂

I'll check out the link you sent for his valk spd tune.

Would Brago be able to handle UNM at R5 you think or do I need to R6 him? I'm trying to progress in my hydra teams too as i'm pretty useless there 😂

I have a lot of 5-6* gear options but I'm so used to leech that I've forsaken (sold) most of my decent lifesteal gear. My clan tells me prioritize stats over sets. 

So maybe I'll trade out your recommendation of Ninja for Geo and the empty slot with Razel with his leech capabilities.

So Valkyrie, Brago, Duchess, Geo and Razel. Who should lead? Brago? I'm not entirely sure Razel matters in the spd tune does he? His passive increases his spd So he just ends up basically being a (de)buffer and DPS because he can cycle through his skills fast enough to keep everyone under inc spd/acc like 90% of the time which is handy since the DL is immune to dec spd. Or should i steer away from inc spd if im gonna do a counterattack/spd tune?

So many variables 😂🙈

Twas indeed.  

If you aren't going for the faster speeds, I would steer clear of Rabbit because he will constantly outrun the shields and the CA and he will get smoked, which will force Duchess to revive and then both of them will totally break the speed tune. 

If you are going for the faster speeds, then you can still use Ninja. I run my Ninja in CB at 266 speed.

If you can stack enough Defense, you do not need Leech or Lifesteal, but I do not know where you are at for gear quality, so that is why I qualified that above.  

You will need Brago @ L60 to get the T6 Mastery (Warmaster) and to build his Defense high enough to turly benefit your team with his passive.

If you are going to run with the slower speeds, Geomancer & Venomage would make an excellent pairing.

As far as Hydra goes, Brago will also serve you well there:  AoE Dec Atk, AoE Inc Def, AoE Provoke, and his Passive will be very strong if you are "mostly uselss" in Hydra right now.