Extra 1d8 of fire damage due to the crit: 3

(OOC: Hot dang! Does Rhogar even need to act with those hot rolls!?)

Though torn for a moment between wanting to aid Vellynne or destroy the ravenous specter of death, seeing Krom having the former well at hand earns the dwarf a curt nod of thanks before the dragonborn rushes off after the creature! A distance he'd rapidly close in an instance upon turning into a golden mist with electricity crackling and dancing throughout it, before then reforming beside the creature mid-lunge for a tackle and grappling maneuver. 

Movement: Full 30ft after fleeing creature.

Bonus Action(if needed): Cast (2nd level)Celestial Step to close as much distance as possible.

Action: It's Wrangling Time with a mighty 15! (18)

(LOL. I never thought of grappling the creature!! I Kazri could do that if the vines fail.)

Dex save 20

Dex save 23

Chill does not need to move to line up his shot and let's a bolt fly that strikes true.  Kazri chases after the creature and tries to ensnare it with spectral vines but the creature breaks through them.  Krom also leaps into action and gets a hit in on it.  Rhogar also chases after the creature and grabs a hold of it.

But as he grapples it the creature suddenly changes into a fine mist and his hold on the creature is lost.  The mist moves through the rest of the chamber and down the south passage that leads out of the cave.

No AOO as it disengaged

"We have to finish it off. That creature is too dangerous to be left unchecked." says Krom as the creature turns into mist and flees down the south passage. As he waits for the opinion of the rest of the group, Krom tries to recall any information he may know about undead that transforms into mist.

"Cursed creature! That's it! I'm not having another one of these sneaks get the drop on us again!" Rhogar declared, though his words somewhat distorted by the crackling of electricity building up in his throat. However, just as it looks as if he might give chase after the mist, he's stopped short by sudden epiphany that prompts him to look back to the party. "... At least, that is what I desire as well, Master Krom. But Vellynne there is no real condition to warrant the risk of pressing our luck, I suppose. So, shall we try rest here and fortify as best we can? The way back is not exactly safe for retreat, but I doubt even the most willful of this place denizens casually trek through the space of that... entity behind the ice. And, this would give me some time to send the eye out on a more thorough investigation of the nearby areas, if nothing else."

Chill moved into the chamber ready to chase the creature. "It will continue to do these hit and run tactics unless we pursue it.  We injure it but it flees and seems to no longer be injured, or at least not injured enough when it returns.  It continues to haunt us, we should put a stop to it." Chill argues in favor of pursuit. 

"Do not worry about Vellynne, Rhogar. Knowing that we would not have the luxury of resting too much, I have prepared a hymn of healing that will patch her up in less than a minute." says the dwarf confidently. He immediately begins to chant the hymn, causing Moradin's holy symbol to glow with a warm reddish light.
The holy symbol brightens at periodially intervals sending waves of healing energy that rapidly begins to heal the wounds on the wizard.
"Let's resume our chase my friends, we have to stop it." says the dwarf gripping the war hammer.

Aura of Vitality on Vellynne (if she is fully healed before the end of the spell, I'll heal Chill)

"I also do not need to rest. I am fine hunting the creature down, if we are all in agreement." Kazri asks Oli to stay close to Vellynne.

Rhogar grimaces, then turns on Vellynne once more, cocking his head this way and that as he studies her condition even as Krom went to work. Eventually, he emits something close to a throaty growl before turning to the rest of the party with a curt nod. "Very well then. We hold for this minute and no more. I'll send the eye ahead in the meantime, and-..." Following a sharp intake of air through the nose, the dragonborn exhales a dark cloud of golden mist that swiftly condenses back into the form of Gorrah. 

With a chirp of excitement, she zips over into her customary perch coiled about the Dragonborn's neck just as the sorcerer sends the eye off down the path the hyena creature ran off down. "Truthfully, I'm not entirely convinced the one we saw is necessarily the same one. But if such proves to be the case, we will have a fight worthy of recognition even by Tempus himself." He said with a chuckle and a wry smile.  

"No mater how many of those creatures, we shall defeat them Mr. Nimbatuul. Where next?" While Vellynne rests, Kazri checks their current location.

Perception: 10

"The creature has taken the south passage." says Krom gesturing towards the passage "It may not be the same creature, but nevertheless we have to defeat it."

"I can keep going.  I'm am barlely hurt and it's original attack has not left me in terrible shape.   Even the effects of that creature have worn off.   But what about Oli?  Was he not also affected?  Will he follow us?" Chill remarks

While the party debates what do to about chasing the creature they must also confront the reality that Oli, while dragged forward out of the previous cavern is still unresponsive and will not walk willingly.

Rhogar sends the eye down the south passage.

He sees a grove of frost-covered trees fills this fifty-foot-high cavern, the floor of which is a mixture of earth and ice. By some magic or miracle, the trees are alive, their canopies thick with frosty leaves, their branches bearing purple pears that hang like ornaments. A low wall, broken in several places, threads its way through the grove, which is surrounded by six exits.

Many places to hide, many places to search.

"I may be able to help with Oli, but.... what is... trees?" Rhogar recoils for a moment, taken aback at the sight seen through the sensor. But after taking the briefest of moments more to look about the chamber for the eyes new position, he grumbles and crosses his arms. "There's a grove -- a living, if albeit strange grove to the south with several exits leading away from it further still... and no signs of the creature, alas. But we'll have to investigate."

With that, Rhogar sets his own eyes on Oli, pulls out the Bell Branch, and with a curt incantation and a boop to the head, he releases some of its magic into the creature in hopes of suppressing whatever grasp the frozen entity from before had on the poor cub.

-Spending another charge of the Bell Branch to cast Protection from Evil and Good. Which normally has to be done preemptively to get the full benefits of it, but hoping within the next minute, if nothing else, peeps are already to figure out a means to prompt another save so Oli can do so at advantage with the spell.

"A grove within this cavern complex? That is indeed strange, Rhogar." replies Krom "However, since the creature fled in that direction, our next steps are clear. We have to find its lair as soon as possible."

"Hopefully, Oli, with the aid of your enchanted branch, will regain his senses. If that proves insufficient, we will have to wait for at least one more day, as the hymn of restoration I performed on Chill is quite taxing, and I cannot execute it properly again today." continues the dwarf as the dragonborn uses the bell branch on the owlbear.

"Chill, your keen senses are more than sufficient for locate the lair of that undead, but allow me to enhance them further with Moradin's blessing."
Krom lays an hand on the tabaxi's shoulder while chanting an hymn of guidance.

Chill nods.   "I'll do my best.   If there is some dirt or more than this hard ground it will be easier to track."

Chill looks back at Oli.  "I'm worried about Oli.  Those tentacles that touched my mind were freaky to say the least.   Poor Oli probably has no idea what is going on."

When the time comes Chill moves forward and studies the ground trying to track the creature that had attacked them. 

Survival 17

Kazri is too buzy concentrating on the creature that got away, that she didn't realize Oli is still unresponsive. With all the "uncles" taking care of the Owlbear, she is not too worried, however she gets closer and see if there is anything else that she can do.

Medicine: 16

Rhogar casts his spell but it seems to have no effect.  Kazri takes a few moments and studies Oli to see if she could figure out what is wrong with Oli.  Chill can give some insight.

Oli is charmed.  Whatever creature lurks behind the the translucent wall in the cavern you passed through earlier has reached its tentacles into the mind of Oli and taken control of his mind.

Kazri also theorizes that pain may break through the charm, or at least give Oli the chance to be free of the charm.