Quillary closes her eyes, touches the cat skull at her forehead, woven into her hair, and brings her hands out, then up. Her spores, looking so much like ash, swirl up and around all of you, and the world dims momentarily, sound deadening, a slight chill on your skin. Her eyes snap open. “Let us go.”

(I just want to be certain:
Quillary has cast Pass Without Trace, and the group is headed down the stairs slowly to be stealthy, hugging the walls or any other cover.
Is that correct?

Make 3 rolls: Stealth (with +10 for PWT), Perception, and Initiative (for later on). )

Drusk 3 rolls:

Yes, this is what I think is happening. Quillary is happy to go first, and will do so unless anyone else stops her.

Quillary's rolls:

Jorin:

• Stealth: 23
• Perception: 11
• Initiative: 18

Stealth: 28

Perception: 22

Initiative: 25

The tower and its basement levels are of ancient construction, their original purpose long forgotten by the area’s residents.
Ceilings throughout the temple are 10 feet high and flat.
All areas of the temple are illuminated by braziers, lamps, or magical light.

The stairs descend thirty feet before opening up into a chamber of worked stone. Two braziers flank the entrance, burning with an unnatural aquamarine light. Pillars stand in two rows, each carved with the visages of otherworldly creatures. A fountain flows quietly at the far end of the room in front of a double door. Another door stands along the west wall, and the wall opposite that appears to have collapsed, revealing a rough passageway beyond.

Quillary and Hildigrim advance slightly ahead of the others. (They also rolled much better on Stealth, which helps.) Crouching next to the braziers, they notice 4 humanoids (mixed races and sexes) near the fountain, tossing dice and gambling with copper coins.

As Q & H look around more, they see Drusk gesture for them to stay as still as possible. A hand-span away from their  eyes are a tentacle probing the air. You can feel a static electricity as it almost touches them, then moves away. The tentacle is barbed, with a dark oily substance coating the tip. Looking carefully around the side of the brazier, Q & H see two medium sized creatures. They look like bulbous brains with a wide, sharp beaks and ten long tentacles, levitating above the ground. (Monster manual image for Grells.)

These creatures don't have eyes, and they notice something is off. But Quillary's concealing spores seems to have them confused for the moment. They are probing the air near the entrance, and also touching the walls and floors checking for vibrations. These Grells are waving their 10' long tentacles around the entrance.

The cultists to the south notice the creatures are agitated, and reach for their weapons. After glancing around the entrance, they don't notice anything. (Pass Without Trace has full effect on them.) "Those monsters are annoying, reacting to every bug and bird that comes down the ramp." They relax, and return their attention to the gambling, letting the Grells continue their actions.

(You can discuss what to do next, but don't get too complicated.
I assume the group has pre-arranged hand signals to communicate basic ideas, so you are doing that.
You can do a frontal attack right away, or you can strategize about spells, targeting, movement, etc.)

OOC > Welp, PWT is concentration, so Quillary is just in for hitting things or Wild Shape (because I think we can maintain concentration on a spell cast before Wild Shape) but that's a poor bet because Quillary has more hp than anything she could Wild Shape into... or would she not lose concentration if her Wild Shape dies and she reverts? Weird. Or spells that don't require concentration, which are mostly cantrips, healing spells, and the way overkill Erupting Earth or Blight. Should save those for something bigger.

Quillary indicates through signs that she is for hitting things now.

(I forgot to mention it earlier, but the 4 in the south are wearing leather armor and carrying scimitars. If that makes a difference.

Wild Shape does not require concentration and does not interfere with spell concentration.
I believe that a common tactic for moon druids is to cast Call Lightning, then shape into an earth elemental for the extra CON bonus.)

Jorin makes a few quick chops with his right hand, and then wiggling his left hand fingers in a walking motion to the right, before "kicking" the right hand with the "legs" of the left, clearly indicating a desire to kill the grell to our right (G1). 

He then, having run out of hands, bites his left hand, clearly signalling that G2 should be the second monster to focus on. 

Quillary has to tap Hildigrim on the shoulder rather hard to get the halfling's attention back from staring raptly at the strange floating beaked brain. He grins and mouths "Sorry" before looking at Q's and J's suggestions. Hildi taps his chin and then indicates that he could use a spell to try to delay the other brain thing in case it takes a few attacks to take them each out. As the creatures are already fairly aware that they are there, it's hard to imagine one remaining blissfully unaware as the other is attacked. However, he will have to speak, which means even if the two-legged enemies can't see him, they'll know at least one person is there.

He also puts forth the idea that they could back up higher on the stairs and attack from a distance. Using movement and continuing to be protected by Quillary's spell, they could try to take out the four from a distance. Even if they rush to the stairs, they'll be stuck in a bottleneck and should be easier to take out.

Quillary thinks hard. Somehow, she signals that she is concerned about reinforcements, but again, she shrugs like whatever is fine as long as she gets to hit things. Backing up the stairs seems like a prudent idea.

(Even though the Grells are the bigger threat, Drusk mimes taking out the 4 cultists first.

The cultists didn't put a guard up in the tower, and these four are focused on gambling more than guarding the area.
Backing up the stairs will lose the element of surprise, and give them time to alert everyone in this temple.
If there is another exit besides this tower, then the Lord Viallis might escape.

Drusk has the spells Silence and Hold Person, if either of them will be useful to keep the 4 cultists from sounding an alarm.)

Jorin nods at Drusk's assessment.  If the cultists got away to sound an alarm, that would be bad.  Its unlikely the brain monsters would do that, so perhaps an all out blitz on the cultists is the way to go.  Maybe a silence spell in the middle of them to keep them from yelling whilst being slaughtered?

Quillary nods at the idea of Silence, and grips her cudgel tightly. No backing up then, rather a rush of the four, with special attention for the beaked brain on the right… or was it the left…

She finger-debates with Jorin about who will go for the four, and who will go for the beaky brain.

(When you are comfortable with your decision, then Hildigrim, Jorin, and Quillary can post their turns.
Drusk didn’t roll as well for Initiative, so is slower out of the starting gate.

After this turn, Hildigrim goes ahead of the other two, but for this round, you can go in any order you want.)

Jorin finger wiggles that we should all rush into the four, kill them as quickly as possible, then turn to the brain monsters.  If Quillary doesn't think that's a good idea, then he'll defer to her judgement and suggest he take on the cultists and she can take the brain..

Oh, no, Quillary loves that idea. She nods decisively, taps her cat skull with her cudgel, which sheds a layer of ash, revealing polished wood. She looks at Drusk to cast Silence, before initiating combat.

OOC > Can we do that, delay until Drusk casts Silence?

Quote from Mingofaust >>

Oh, no, Quillary loves that idea. She nods decisively, taps her cat skull with her cudgel, which sheds a layer of ash, revealing polished wood. She looks at Drusk to cast Silence, before initiating combat.

OOC > Can we do that, delay until Drusk casts Silence?

(Drusk has initiative 10. For this first round, he will cast Silence as directed to set things off, but then go back into initiative order.)

Assuming that Hildigrim agrees with this (although maybe a bit reluctantly), Drusk casts Silence 5' north of the fountain. The grells become more active due to the sound of the spell being cast, but the cultists in the south haven't noticed as they are yelling their bets on the dice rolls. The 20' radius sphere covers the doors to the south and west, and the opening on the east wall.

It stops just short of Quillary and Hildigrim's current position. The only spots in the room not covered are the squares that the grells are in. They are probably growling, their beaks gnashing and clacking, but if they are making any noise it cannot penetrate the spell area. Although you can hear faintly the wind blowing over the entrance mouth of this tunnel, the crackling of the brazier fires has gone away.

(Everyone is up, except for Drusk.)

(Edit: For this round, Quillary and Hildigrim have advantage vs all of the cultists, due to their stealth rolls. Consider them blinded.
Jorin has advantage on C1 and C2, as their backs are turned. But if he is charging into melee range, for C3 or C4 it will be a normal attacks as they will see the silhouette of Jorin backlit by the brazier fire.)

Jorin will charge in bringing his blades to bear on C1!

• Movement: Rushing to C1
• Bonus Action: RAGE
• Action: Battleaxe!
  • First Attack: 19 Damage: 13
  • Second Attack: 24 Damage: 16
  • +5 radiant damage to the first strike that hits

Quillary hefts her shield and charges after Jorin, diving into the middle of them, reaching out to tag one of the cultists with her club, her spores swirling at the other.

Move: 5 south and 1 east to the square next to C3 to the inside
Action: swing magic club at C4 with advantage. 23 to hit, for 13 magical bludgeoning damage
Bonus Action: Nope, here's wishing we could attack with a shield, but it wouldn't be a light weapon, anyway.
Reaction: When C3 starts his turn, Con Save vs DC 16 or take 4 necrotic from Halo of Spores