As the strange figures reveal themselves, Krizira and Techlas are the first to leap into action...

Initiative Order: Krizira -> Techlas

Krizira holds up her hand. In a soft voice she says, "I'm not sure they're attacking us. Does anyone know anything about a Singer or King of Bones? Perhaps if we just leave the bag alone?"  She's skeptical and so readies her longbow, aiming for the shadowy figure closest to her to her left. (READY action to fire should any of the shadowy creatures start to attack anyone or if her companions start attacking.) 

(Longbow Attack: 15, Damage: 5)

(OOC - If she can, she would try to recall anything about a Singer and King of Bones. INT Check: 8) 

Ash telepathically sends Xarian a message of approval for Krizira's actions, if not her words.  If these hidden shadows did not wish us harm, they would have stayed hidden, or met us openly.  No friendly creature behaves this way.

Using owls' Flyby capability and 60' of movement, she flies 45' north-northeast from Xarian's shoulder and takes the help action on the shadow that Krizira aimed at (assuming it is still there, otherwise the other one).  Ash then uses her remaining 15' of movement to fly upwards and southwest, taking cover in the foliage of the tree there.  No opportunity attack incurred due to Flyby and the next attack against her target is at advantage.

"You've got this Xarian, I believe in you!" Techlas calls out from behind the others, inspiring the young warrior (Bardic Inspiration). He squints his eyes in the same direction as Krizira, looking at the robed figure next to where she's aiming. whispered words fall from his lips, attacking the stranger with a psychic attack.

WIS SAVE: 2
Damage: 17

You would all see the figure clutch their head, spasming silently as they fall to the ground.

Initiative Order: (Waiting for Krizira's second roll and then I'll continue)

(Krizira 2nd Attack roll: 22)

The man is speaking gibberish to Krizira's ears. Singer? King of Bone? Sounded like occult nonsense.

Silently, two of the cloaked humanoids begin to move, and Krizira lets her arrow loose. It catches her target in the torso, who stumbles backward but remains standing. Brandishing curved short blades, the pair begin to move towards the center of the clearing. Their movements are fast, precise, and waste nothing - yet there is something of a grace to them. You feel as though they're prepared to dodge any attack you may make towards them.

(Attack rolls against the two nearest Richter and Xarian have disadvantage)

"Look how they kill. It is blunt. Their instruments send out harm and take nothing back. Your blades however, will be as a bridge." The disembodied voice speaks out once more, and a fifth figure quickly materializes at its source, holding a hand crossbow pointed at Richter. 

Hand Crossbow Attack - Richter
Attack: 23
Damage 6

They're moving quickly before the bolt even finds or misses its target, swinging southwest.

Initiative Order: Richter -> Sylnora

((I don't want to edit the post so the dice rolls are not messed up, but to clarify: The figure who appeared in the center is able to take dash as a bonus action, and that is how they're able to move so far/fast.))

Richter grits his teeth as the bolt finds him, using his free hand to rip it out. "Blunt huh?" He circles around Xarian(ending up just southwest of him), eyes locking onto the who just shot him. 

He reaches for the power granted to him, placing a Hex(strength) on the cloaked figure. A red energy gathers in his hand, lancing forward with a loud crack across the clearing.

Eldritch Blast
To Hit: 15
Damage: 8(force) + 3(necrotic) = 11

Sylnora fires off a fire bolt at the ambusher Krizira had already injured before moving further into the clearing to join Xarian and Richter.

Action
Fire Bolt Attack: 24
Damage: 4

Movement
 30 feet E.

Just after Richter's spell takes hold, the crackling beam of arcane energy that follows strikes the speaker in his abdomen, and you hear a gasp as the air is knocked from his lungs. Meanwhile the remaining cultist to the north is dropped as Sylnora's fire bolt takes him in the face, dropping him instantly.

Sharp, ritualistic words in a language none of you understand ring out through the clearing now as one of the cultists steps forwarding, invoking a a spectral weapon in between Xarian, Sylnora, and Richter. It takes the form of large greatsword, fashioned from bone and shaped like an oversized cleaver. It pulses with a green glow, and swings down with surprising speed at Richter.

Spiritual Weapon Attack - Richter
Attack: 7
Damage: 3

More words fall from the caster's lips, and a green sickly radiance descends upon him next.

Sacred Flame Attack - Richter
Dex Save - (11 DC)
Damage: 1

The figure then moves east, stopping just southwest of the crossbow-wielder.

Initiative Order -> Xarian -> Krizira -> Ash -> Techlas

Richter parries the ghostly greatsword with his own blade, spinning out of the way as the green fire crashes down where he was standing.

Dex Save: 12

Xarian bulls south through the space of the spectral bone greatsword, S-->S-->S-->S-->SE.  (So he is just SW of the nearest cultist).

He mumbles and wiggles his hands somewhat absurdly on the haft of his maul as he draws it, and a blue thunderous energy haltingly emerges to surround the weapon (Booming Blade).  Looking almost relieved that it worked, he brings the massive maul around two-handed into the cultist's chest.

Xarian's voice, if anything, sounds a little hurt.  "What have you got against blunt weapons?"

Maul to hit cultist (at disadvantage due to cultist's dodge action):  15
Maul damage:  15 bludgeoning
Crusher Feat/Forced Movement:  on hit, the cultist is smashed 5' northwest towards Richter and Syl.
Booming Blade secondary effect on hit:  if target moves willingly (not forced) before Xarian's next turn, they take 4 additional thunder damage.

Assuming he is now out of melee, Xarian finishes his movement 5' further south towards the two remaining enemies (that he can see, anyway).

The cultist chest caves in as Xarian's maul strikes its target - he's lifted off the ground and sent flying back towards Richter and Syl. The body lands on the ground fight feet away, motionless and lifeless.

Initiative Order --> Krizira -> Ash -> Techlas

Krizira again knock an arrow to her bowstring, aiming at the cultists on her right of the pair far to the south. 

(Longbow Attack: 13, Damage: 8)

If it hits, she triggers an arcane burst from the arrow. (6 force damage to the target and all other creatures within 10 ft.)

Ash flies due south 60', from one tree to another, attempting land on another branch within the foliage for some cover.  She avoids getting too close to the spectral bone greatsword which is nearer the center of the clearing.

As she flies, she looks and listens for any other hidden figures or hazards not already apparent, telepathically communicating her findings to Xarian.

Ash Perception at advantage due to owls' Keen Hearing and Sight:  22

The arrow fired from Krizira's bow streaks through the air, catching the cultist and exploding in a burst of arcane energy. The crossbow wielder is caught in the blast, nearly getting thrown down. The hood of his cloak falls off, revealing a bald elvish man. Blood drips from his mouth, and he seems to be just barely hanging on now.

Ash hears nor sees no sign of anyone else hiding in the area.

Techlas steps forward, uttering more arcane words followed by a Command, "HALT!"

The magic command seems to have no effect on the pair. 

The elvish man put his hand on the shoulder of the other cultist, whispering something before flipping his hood back up and turning to retreat into the darkness. Initially you're still able to hear his movements and guess his general location even as ducks behind brush and leaves the range of your dark vision, but at some point you simply lose track of him. Even Ash, who is able to see much further in the dark isn't able to keep up with his stealthy movements. 

Initiative Order:  Richter -> Sylnora

"Tch, fat load of good your blades did it looks like." Richter says, disappointed that the talkative one would flee. Perhaps they could track him down after finishing up here. 

He turns his attention to the last remaining cultist and moves forward to join Xarian. Another lance of red arcane energy leaps from his palm, streaking towards the enemy spellcaster.

Eldritch Blast
To Hit: 13
Damage: 14(force)