Rhayna Investigation: 25
The shrine appears to be dedicated to Mystral, the goddess of magic. The friezes on the wall seem to pay homage to Mystral's origins from Shar and Selune, and are not a dedication to those goddesses per se. The only conclusion Rhayna can draw is that the person entombed here (presumably Brysis Khaem herself) was a devotee of Mystral. The fact that there are two doors probably suggests one leads to the tomb itself and the other leads to a treasure chamber. Alternatively, some Netherese nobles were entombed with their servants, so the second room could be a tomb for the servants.

Zeno: Neither of the doors appear to be trapped.

Joetaro turns to the shrine and takes a bow before it, whispering a prayer to Selune.

Sekkar shrugged and got a coin from the pocket. "Heads - left, tails - right." He flipped the coin 1 , loudly announced "heads" and tried to open the eastern door - the one opposite to the staircase.

The eastern door opens into a smaller chamber, dimly lit by faerzress. In each corner is a stone sarcophagus, the lids of each bearing the sculpted image of a robed human figure in repose. 

"More long dead" Sekkar was torn between wish to check that sarcophagus - and reasonable warnings from Kastix about spirits, possessing curious. He listen for the voice - is it even here still? - and asked the group: "Want to open one to see what's inside?"

Rhayna bows to Selune’s frieze and goes into the eastern chamber to see if there are more interesting things to discover.

Kaylyn stands near the doorway and peers into the room.  She again casts Detect Magic and then calls out "Hello?  Anyone here?"

Sekkar and Rhayna enter the room, looking curiously around the chamber, albeit for different reasons. Kastix, Zeno and Joetaro linger in the shrine room, while Kaylyn looks in through the doorway and casts her spell. No sooner has the warlock incanted her spell than there is a bang and a puff of smoke, and Kaylyn appears to have vanished. In the place she was standing there is now a small ceramic pot of soil, out of which grows a two-foot-tall toadstool with orange and red stripes across its beige cap.

Sekkar recognises the variety of toadstool, but has no time to recall its name as the explosion appears to have disturbed the denizens of the sarcophagi. From each corner a malevolent spirit rises, and with a look of sad, jealous hatred in their glowing eyes, they reach out their spectral hands toward the cleric and the ranger...

Roll for Initiative! Four specters act on 12. If you roll higher then post your actions. If lower, then you can post if you like or wait for the outcome. I've imagined Sekkar by the north wall between two sarcophagi, Rhayna likewise on the south, the toadstool in the corridor just past the door, and the others somewhere in the shrine room, but feel free to place yourself anywhere. The squares on the map above are actually 10'x10' so plenty of room.

Sekkar Initiative: 24

Sekkar never trusted magic. Can be useful - very useful indeed - but too unpredictable and brings all kind of troubles. Also, he did not really know how to fight it. His first instinct was to run, but those things looked like they can follow through the door. So, he simply tried everything he had:

Bonus: Hungry Jaws: Attack: 24 Damage: 6

Attack: 22 Damage: 10

Attack: 10 Damage: 11 + 1

Joetaro Initiative - 13

Kastix Iniaitive: 13

Zeno Init: 9

Zeno was surreptitiously eyeing various parts of the shrine trying to determine if there was anything valuable when he heard the bang from the doorway, and the shouts of surprise from his compatriots in the other room.  He drew his crossbow and ran to the doorway. He felt like his breath was sucked from his lungs as he stared, then quickly fired a bolt at one of the specters by Rhayna.

Bonus Action: Hide (Stealth: 10

Action: Hand Crossbow: Attack: 15 Damage: 10

Sneak Attack: 4

Kaylyn Initiative - 14

Kaylyn gasps for air as she changes back.  Seeing the danger she fires a blast of energy at the spirit in the bottom right corner.

Attack: 12 Damage: 7 

Rhayna Initiative: 16

Rhayna brings up her pendant and yells. “Begone foul creatures!!” (She uses her Channel Divinity: Turn Undead)

ROUND 1

Of the four spirits, the two in the north of the room are clearly the more powerful. Sekkar engages his instincts with a vicious attack on the largest and most malicious spirit, and although his jaws and blades seem to pass without resistance through the incorporeal creature, still it hisses with rage and it retaliates as it saps the life hungrily from the lizardman.

As Stool hunkers down in her backpack, Rhayna abjures the undead to flee by Selune's light, but only the smallest and weakest lacks the will to resist, and it flies from the room toward the stairs. The next-largest resists but only barely, and its subsequent attempt to feed on Rhayna's life-force is weak and easily avoided, after which Kaylyn's arcane bolt carves a smoking hole in its misty form. However the larger one in the north turns in rage and floats over to Rhayna with a voracious gleam in its eyes. With an extended spectral hand it feeds on the cleric's vital energy, leaving Rhayna withered, weak and very close to death.

Sekkar has one specter attacking him (#1 the biggest and baddest), and must make a DC 10 CON save v the Life Drain. Sekkar can also make an opportunity attack against #2.

Rhayna has two attacking her (#2 and #3), is in very bad shape, and must also make a DC 10 CON save v the Life Drain.

Opportunity attacks can be made against #4 as it flees, but this will negate the Turn Undead effect.

Sekkar Con save: 19

AoO: Attack: 21 Damage: 10

Kastix moves to seeing what's going on before firing Scoring rays, all 3 into Specter #2.

#1 Ray Attack: 10 Damage: 6

#2 Ray Attack: 19 Damage: 10

#3 Ray Attack: 20 Damage: 4 

Using Empowered Spell to reroll damage where I assume a 1 was rolled, (i can't see rolls)

#1 new Damage: 8

#2 new damage: 4 + 3 = 9 total 

Joetaro is going to run to Rayna's side and use Lay on Hands to heal all 20 points for her.

Rhayna CON Save: 12

Rhayna keeps her back to the wall, to protect Stool. She holds her Journal to her chest and her pendant high. (Rhayna takes the Dodge action)

ROUND 1 cont...

Kastix, Zeno and Joetaro see a single specter flee toward the stairs and hear the commotion from the next room. As they race into the room to help they wonder if their eyes are playing tricks on them as they see that there appears to be four separate Kaylyns in the small corridor. Weaving around these unexpected duplicates, Kastix bursts into the room, sees the baleful spirit drawing the life from Rhayna, and unleashes three rays of searing flame at it. The specter shrieks an unearthly wail and dissipates into the ether, leaving only a black scorch mark on the wall behind it.

Zeno enters the room next, takes a crouching stance behind the first sarcophagus on the south, and fires a point-blank crossbow at the specter with the fresh hole from Kaylyn's eldritch blast. Which continues to glare hungrily at Rhayna. From the doorway Joetaro assesses the course of the battle, recognises the area of greatest need, and bravely crosses in front of the remaining specter beside Rhayna and channels Selune's light into the cleric, restoring her vital force.

Al_the_bard: In addition to Lay on Hands, Joetaro can also cast a spell as a bonus action if you want, such as Sanctuary on Rhayna if you want to protect her from further attacks, or Searing Smite if you want to prepare for a melee attack next round.

Paladin54: You are now in control of three duplicates of yourself as if you cast Mirror Image.

Sekkar and Kaylyn's actions...