"Hmmn.  Just as I suspected..." Varan says, again to no one in particular.  He turns his attention to these strange patterns.  Does any of it look familiar?

Mulligan attempts to wind an abjurational incantation through the air, though a distinct - if anticlimactic - fizzling of his spell indicates whatever magic poisoning the air still remains. 

If you have something which grants you resistance against magic, you would have advantage on the saving throw. 

With the chittering whispers of Vorax, Avarice manages to gain headway on the puzzling array of ridges and bumps crowning each of the four pillars, only really discernible by touch; each tells the same message, though all in different languages - one in thieves' cant, another in celestial, the third in morse code, and the fourth in a magical standard of writing known as 'mage's margins', reading; "The answer you seek requires you to cease fighting something which harms you. Forgo your sight, and the answer can be seen."

You know the drill - damage, 13, DC15 Constitution save half. 

Varan only, please make me a Wisdom saving throw. 

In the other room, the blood of Ragnar, Wulgar, and Keyleth spill on the ground in turn. The runes glow and pulse as if they are alive - the blood sizzles, though not with heat, and trace along the spiral-like patterns, magnifying and filling in the runes carved on the floor below. 

The bubbling mass swirls and coalesces in the center, almost appealing to congeal at an accelerated rate. The swirling mixture combines with blue sparks of energy before splitting into three distinct forms. 

Entirely bloodred and otherwise colorless, perfect replicas of Keyleth, Wulgar, and Ragnar stand as if you are looking into a mirror, weapons drawn and at the ready. Their expressions are vacant and blank - mere shells of the beings they are derived from; shells of the beings they are here to test. Blood drips from their crystallized armor as they move with the exact cadence of the beings they emulate; Keyleth's replica is already drawing swords and analyzing which target to strike first, Wulgar's replica seems to be heaving breaths - with clouds of mist billowing from its red snout, and Ragnar's replica seems to hold his sword high, preparing to strike downwards with brutal force. 

Roll initiative!

rangaR initiative: 20
htelyeK initiative: 19
ragluW initiative: 16

Wulgar initiative :  17 

Wulgar pulls out his great axe and gets into a ready stance, flying into a rage at this clone of himself.

Mulligan Con Save: 22

     Torn between trying his spell again and checking out what Avarice is calling him over to, Mulligan decides on seeing what it is the Tiefling found. Upon being directed to the bumps and ridges, Mulligan will inspect them like the others.  "I can read the Margins but the others are unknown to me," Mulligan fibs while of course double checking that the Thieve's Cant reads the same as the Mage's Margins.  Mulligan will then close his eyes, step back, and...  try to breathe regularly?  For the poison is the only thing he has been fighting...

Keyleth curses and draws her shortswords.

Keyleth initiative: 11

(OOC: As Kaemgen pointed out, question is still if Vorax gives Avarice magic resistance or not.)

Ragnar looks at the mirror image of himself, at the old creases on his face and his graying hairs. He didn't realize that he's grown so old, and the thought of his mortality sends a shiver up his spine. 

"I've gone time left. I'll prove that today."

He draws his ancestral Frost Brand and prepares for battle. 

Initiative: 11

(OOC: No, Vorax should not grant advantage to resist magical effects and saving throws, if that's what you mean. I will update the other room when Varan has posted.)

 Initiative Tracker:
Wulgar - 17
rangaR - 15
htelyeK - 14
ragluW - 12
Keyleth - 11
Ragnar - 11

You're up, Wulgar. 

Wulgar steps forward one square (close enough to catch all 3 with this effect) and shouts in a roar at the three figures, it is jarring to the ears.  

He breathes hot fire out of his mouth in a cone, scorching the three clones facing him to begin the combat.  DC 17 dex save, if a failed save takes 9 damage, half that on a successful save.  

Wulgar then flies into a rage, yelling at the three of them in a bellowing roar.  

rangaR Dex save (Resistance to Fire [Frost Brand Longsword]): 25
htelyeK Dex save (Evasion, +5 bonus from rangaR's Aura of Protection): 15 (forgot to add her Dex bonus, should be 20)
ragluW Dex save (Danger Sense, Resistance to Fire damage [Red Dragonborn], +5 bonus from rangaR's Aura of Protection): 26

All three mirror-like blood images seem prepared for Wulgar's breath, as if they are in tune with the abilities of their creators. Keyleth's duplicate twitches from the blast entirely, while the other two seem well-guarded against fire. 

The blood-formed Ragnar walks forwards, grizzly expression chiseled and fierce. His blade begins thrumming with crackling energy derived from the magical energy animating the blood as he lets out a cry, raising his bolstered sword in the air and exuding an aura of sheer terror. 
Movement: to tile before Wulgar.
Bonus Action: cast 4th-level Wrathful Smite. 
Action: Channel Divinity - Conquering Presence. Wulgar, Ragnar, and Keyleth - please make a DC 18 Wisdom saving throw or be frightened. You may reroll this save at the end of your turn. Additionally, if you are frightened while within 10' of rangaR, you have a speed of 0, and you take 6 points of Psychic damage at the start of your turn while frightened. 

Keyleth's mimiced form lunges forth, seeking to run a wicked shortsword through Wulgar's abdomen. The blood form collapses on to the ground and reforms on the opposite side of the cavern, shortswords held in a defensive position.
Movement: Down two tiles. 
Action: Shortsword attack against Wulgar. Attack: 28 Damage: 23 piercing.
Bonus Action: Disengage.
Movement: Up four tiles. 

The hulking, scaled figure of the blood-colored Wulgar unleashes a cry of sheer, warbled rage and dashes forth, clawed feet clicking over the stone ground - halting right before Ragnar, the bloodbarian carves down twice with brutal precision. 
Movement: Right one tile, down three. 
Bonus Action: Rage!
Action: Two Reckless attacks against Ragnar. 
Attack 1: 28 Damage: 12 slashing.
Attack 2: 28 Damage: 16 slashing.
If either of those hit, Ragnar takes an additional 11 Necrotic damage as the blade is infused with much more than just pure fury. 

 Initiative Tracker:
Wulgar - 17
rangaR - 15
htelyeK - 14
ragluW - 12
Keyleth - 11
Ragnar - 11

Bold means you're good to post your action. Refer to the text for what saves you need to make and what damage you have taken. I have tracked everything to the best of my ability. Please let me know if anything is amiss. The red aura is rangaR's Aura of Conquest and Aura of Protection for allies, while the blue is the real Ragnar's similar abilities. 

Wulgar wis saving throw :  4 

Wulgar is initially frightened by rangaR, but feels calmed and settled by the real Ragnar, his mouth stays in a snarl, he hefts his axe, getting into position to swing.

CON save. 26

WIS save.  3

“What does this riddle suggest?  We stop fighting the poison?”

…. …. 

“‘Forego your sight and the answer can be seen’… “.   He starts to wonder.  Maybe the poison is… a stimulant?  A hallucinogen?  Perhaps if we embrace the poison we will see the answer?  

Next round, Varan will drop his resistance and intentionally fail the savings throw.

WIS save: 8

Keyleth's heart begins to pound at the sight of these...things, the blood still in her running cold. The bloody construct resembling Ragnar sends a chill down her spine. She can't move. She can't act. She can't think. It's as if it's piercing her mind, and all she can do is stand there, rooted to the spot, unable to even tear her gaze away.

Avarice closes his eyes and takes a deep breath, voluntarily failing his save, hoping to see a way out of this before he soon expires.

(OOC: Ok, thanks, adjusted hp.)

Perhaps he was getting old, as his reflexes must have been slow to allow the duplicates to assault so quickly. He takes two devastating slashes from Wulfgar, but only laughs when rangaR attempts to frighten him. 

He notices Keyleth frozen with fear and decides quickly what to do. 

Movement: To the square underneath the real Wulfgar (avoids OA and extends Aura to Keyleth?)

He says to her, "You would not accept my support before. I offer it once more, and shall not do so again." 

Action: Cast Hold Person at level 3 at the duplicate Keyleth and Wulfgar.

WIS 18 Save 

(Possibly more depending on the saves of ragfluW) 

Varan and Avarice both embrace the poison coursing through their lungs as Mulligan instead makes his best attempt at breathing normally - and all feel the searing poison still take hold. 7 Poison damage. You know the drill. 

Varan only, however, you swear you hear a voice through the cloud - a very familiar one; the choked screams of the 'collateral damage' from one of his missions. He sees a vague shape in the mists - one of a woman, retching on the ground. Her face is difficult to make out, but hanging around her neck is a pendant - and around her neck is a small thread of rope, on which a yellow, topaz-like crystal, similar to the ones you saw earlier, hangs suspended. 

Avarice, when you close your eyes, to you, the property of the room seems to...change. The noises you hear reflected from the walls almost seem hollow, as if there were suddenly spaces beyond the walls of the room. 

htelyeK DC 18 Wisdom save: 24
ragluW DC 18 Wisdom save (+5 from rangaR's Aura of Protection): 20
ragluW's DC 18 Wisdom save reroll (Fanatical Focus, +5 from rangaR's Aura of Protection): 14
The blood-form of Keyleth halts, overcome by the spell, but while Wulgar's duplicate initially freezes in a similar fashion, the blood-red dragonborn lets out a bellow and resists the paralyzing incantation.  

(Apparently DDB doesn't like my editing. For clarity; htelyeK is effected by hold person, while ragluW is not.)

     Despite his best efforts to breath normally, Mulligan stammers and chokes on the poison, his efforts to stop fighting it obviously failing.  Still he has no idea what else to try as the ridges weren't very clear in what they were instructing...  As such, Mulligan tried a Dispel Magic once again since nothing else seemed to be working:  11 vs the DC of the spell (10+Spell's Level)

     Mulligan curses.  Obviously he couldn't cast for crap while choking down this poison!

Wulgar turns to rangaR and makes a cut with his greataxe, trying to disrupt his concentration.  With his second slice, he will turn to ragluW to hack into his simulacrum.

Great axe 1st swing : Attack: 16 Damage: 15  - if this hits, he does an additional 11 necrotic damage.  If the second swing hits first, this damage is added then.

Great axe 2nd swing : Attack: 31 Damage: 27 

Since Wulgar's second hit against his own simulacrum was a critical hit, due to brutal criticals he does additional damage :  15 additional damage.

(So 53 points of damage to ragluW from this attack.)

"I think *cough* that the walls might be a powerful illusion." Avarice calls out, eyes still closed and not aware of the actions of Mulligan and Varan. Guided by Vorax, still sitting comfortably on his shoulder and not the least uncomforted by the green poisonous gas, Avarice moves up to one of the walls and focuses his will on passing through it.
Arcana if needed to determine if the walls are illsions that could be moved through, with help from Vorax:20

Heart still pounding, Keyleth manages to draw her bow and fire an arrow at rangaR.

Shot: 29 Damage: 7