Without a reviver it's certainly harder, but BEK should let you get thru. BEK, UDK, Nekh, Vogoth, and Husk should do it np.

I figured that may end up being my best bet, would you HP tune that team? I just dont know how the boss' mechanics work in terms of how he targets. With UDK taking single target hits, and Nekrhet's AP I feel like things get tricky. With UDK's passive, Im not sure how to keep him alive if he's taking all the damage from every single target hit from the boss....that also ignores def.  

So, from what I remember, dealing with Valks was a pain. I had decent accuracy on Vogoth, so he could provoke and heal UDK somewhat, and I remember hitting CA Valks with Vogoth because they have a 2-hitter A1, meaning UDK absorbs the first hit but the second hit heals him back. Otherwise, UDK eats all the single-hitter damage and Vogoth can't heal him.

Husk was bad affinity, so not as useful as I had hoped, but he is still worth bringing. I'm not too familiar with Nekhret, but he seems great for the boss fight. Careful running AOE A1 with Valks because UDK is eating all that damage, and he won't last long.

It's not a bad point, and if UDK ends up dying as a consequence, just get rid of him. He's not really critical for that team. Replace him with Seeker for more turns on BEK to heal everyone.

Regen + Immortal may be able to help. Also, I'm not sure, but if the boss targets allies with lowest HP and his damage is based on HP, maybe the damage hitting UDK would not be as significant? 

I figure I'll end up running Vogoth in a stun set to hopefully bridge the neg affinity gap. If the Valks are still an issue, I can put Vogoth in a set as well, I'll lose a little damage obvs, but have a stun set that has decent dps. I liked UDK in there as a back up dec atk on the boss, but hopefully Nek will be able to cover if hes out

Im not sure how the boss works, especially when AP is involved. At that point, if the champ with the lowest HP has AP on, does the boss still go after him? Or, is he looking for "highest kill probability" rather than just lowest HP?