CON save: 17

Surrounded again with undead, Hansel again displays the shining shield with the smiling face of Sune...

Action: Channel Divinity: Turn Undead (DC 15 WIS save) against M2-5. By the way, I forgot to mention, if the undead fail their save and if their CR is 1 or less, they are destroyed.

Bonus Action: Shield of Faith on Davis. 

(You forgot to mention, and I forgot to check, but they are above CR1)

Saves: 5,  15,  16,  0 

Math (adjusted)

Yusko, Davis!

Davis takes a deep breath, then strikes at the unshackled seal...

BA Second wind for: 9
Attacks...
Attack: 14 Damage: 8
Attack: 12 Damage: 13

Forgot to say, if either of those manage to hit, an extra 3 from giant's might and 4 from his patron.

Yusko dodges the creature by him and shakes his head as he strikes out three time at the thing.

Attack: 28 Damage: 8

Attack: 29 Damage: 11

Bonus action

Attack: 18 Damage: 10

Invisible animals could be nimble and impossible to see, but too big to miss. Both Davis's hits met the flesh, and a few more strings of blood polluted the water. 

Similarly, Yusko in three to fast to notice moves half destroyed the drowner attacking him. Unfortunately, only half - the rest of the bones and rotten meat were still after the monk.

Round 4 

Math

Map

 Trudie and Nameless One!

Dc 12 con save : 16

Nameless one disengages and backs away 35 feet from the two undead.  (To maybe 8z but 20 feet up?)

“Slippery suckers!” Trudie chimes.

Reaction: Halo of Spores + Symbiotic Entity vs most hurt of M4 or M5 Damage: 5 Con ST DC 16

The old tort would flourish her staff and finish it off with a flick. A chunk of water freezes into a shard, speeding towards the attackers who cuddled up to nameless and explodes.

Action: Ice Knife on M3 to explode to catch its neighbours
Attack: 24 Damage: 1 and Dex ST DC16 for cold damage: 7 

Saves: M5: 18 M3: 5 14

The Nameless girl jetted up and away from the dangerous location, and not a moment too soon - the ice bullet struck the drowner and exploded like a little grenade, piercing the rotting meat.

Just a few seconds later the corals around the group did the same - shooting up and around another stone net that tried to envelop everyone in the wide zone. Even the nimble Nameless girl in the waters above the ground got caught. The attacking drawners (and, not surprisingly, seals as well) were spared, though.  

Everyone!  DC 18 Strength saving throw or become restrained!

The animals immediately attacked:

Seals vs Davis:

Attack: 27 Damage: 17
Attack: 8 Damage: 11
Attack: 15 Damage: 13
Attack: 17 Damage: 14

(Make saves and we continue)

Trudie Strength ST: 15 

Strength Save vs DC 18 : 17 

Davis str save: 29

The first seal hits Davis, the second misses. (His AC is 22 with shield of Faith.) Still, he is now down to 9 HP. The seal in the shackles takes another 7 fire damage at the start of its turn though, if that makes any difference.

Hansel STR save: 14

(My turn shortly, I'll throw some healing at Davis)

(If I am not mistaken, once freed from the shackles, the creature does not get any damage anymore. And the seal made its save)

Yusko save: 26  Vadok: 14 

The corals spread around the livings, pinning most of them down. They were powerless to bind the large warrior, but invisible seals were good enough to keep Davis occupied. Nameless girl was slowly pulled down under the weight of the rocky net around her. Fortunately, away from the closest monsters. Others, still covered from one side by Davis, had to deal only with one drowner. And with the tentacled woman that now dared to appear on the scene again. The deformed mouth stretched in a grotesque grin and the creature bubbled some words that agitated the water around the group, turning it into a whirlpool.

Davis, Trudie and Hansel - DC13 Strength saving throw or get 9 bludgeoning damage. 

Saves: Vadok  19, s1: 19,  s2: 12, M2-M5:  17,  9,  21,  6

M1, meanwhile, continued his attacks on Yusko, who happily avoided the coral trap.

vs Yusko:  Attack: 22 Damage: 6
                   Attack: 23 Damage: 6

The strong pull of water washed the undead away from Trudie and Hansel, whirling them around the group. Something big and soft like a fine fur touched first Hansel, then Trudie - it seemed one of the seals was pulled in as well.

Vadok, glued to the bottom of the sea like everyone else, with the saddest expression on his face shook his head and tried to help the big warrior protecting him from the assault of the creatures. The green light touched Davis again.

Davis gets 16 HP

That was the time when the mermaid appeared on the battlefield again, assessing the damage but not attacking. Instead, she almost demonstratively opened her arms, fully showing the wounds, the crystal on the top of the rod glowed and the wounds closed before the eyes of those who had the luxury to watch.

Math before saves!

Map

Yusko, Davis, Hansel!

Make your saves and don't forget concentration saves if got some damage!

(The site decided to change the numbers (without even the warning) I'll go with the old ones - there were too many to recalculate everything. Yusko made his saves, but got 6 damage instead of 4. Davis had 18 HP healed and ignore saves for monsters)

(Realized this way too late, and probably wouldn’t make a difference but I did post Trudie moved from where she stood to unclutter them from this position back in post #436, but didn’t specify anything and it probably wouldn’t make a difference. My bad there.)

Old cluttered mind and rusty bag of bones ST: 6 

Con save: 12 

Davis str save, vs whirlpool: 15

Davis puts his efforts into striking down the one invisible seal near him...

Attack: 14 Damage: 8
Attack: 26 Damage: 8
Bonus action Attack: 22 Damage: 11