(I assume that's a Con save?)

Con save: 13

It is a con save

(They're really good at those, and pretty good at the other physical saves too... Not so good at the mental saves).

(Yeah I thought I'd give it a go, oh well!)

The maul lights up the inside of the troll's skull, but it seems to have no effect on the lumbering creature.

Ripping it out of the troll's mouth, Tor braces, then returns the maul with gusto, attempting to make a blow to the troll's head, then back again into its ribs.

Maul: 27 Damage: 19
Maul: 19 Damage: 8

If I get a hit, I'll make it a Distracting Strike: +7 damage, and next attack roll against the troll (other than Tor) gets advantage.

Surrounded by hulking trolls and waves of death magic, Brother Siegfried calms his heart.  He clutches his amulet and calls on his deity to help clear this fetid air.  All around Brother Siegfried, angelic beings of shimmering light appear out to a radius of 15'.  They carry tools of the fields: hoes, rakes, axes, scythes.  They dance in a whirling circle around the priest, sparing his allies but punishing these creatures of rot and pestilence.

He moves 5' west, staying within reach of his troll but brining the second troll fully within the effect of his spell.

[Sigi casts Spirit Guardians.  When you cast this spell, you can designate any number of creatures you can see to be unaffected by it. An affected creature's speed is halved in the area, and when the creature enters the area for the first time on a turn or starts its turn there, it must make a Wisdom saving throw. On a failed save, the creature takes 3d8 radiant damage.  On a successful save, the creature takes half as much damage.]

Rot trolls Wisdom Saves: Attacking Tor 10; Attacking Brother Sigi: 11

22 radiant damage

The trolls seem overwhelmed by the sudden ferocity of their prey and how quickly the tables turned on what they thought would be an easy meal. Missing it's attack on Tor and finding its mouth around a hard maul rather than tasty flesh, it's suddenly burned by the ball of fire that grows from Vandeyr's flask, rushing in to burn the southern troll. Before it can even react to the burns, Rawlings' eldritch blasts slam into the monster, nearly knocking it down from the force. As it gathers its wits, Tor slams the maul into the troll's skull, knocking one of its tusks clean off. His backswing crushes the brute's chest; it spits green blood as multiple ribs puncture its lungs. The troll drops to one knee, glaring angrily at Tor a second before a spectral reaper's scythe cuts through its chest like so much wheat. While the scythe does no physical damage, there's a hint of a black soul being sliced in two. The light leaves the creature's eyes and it collapses in front of Tor, leaking lifeblood and ichor into the swampy waters.

The other troll, sliced by the angelic farmers, roars in pain and anger, it attacks Brother Siegfried, not smart enough to recognize the danger it's in. With the death of its fellow it only sees no more challenge to its meal, if it can kill the party.

Bite: 11 Damage: 9 piercing damage + 26 necrotic damage
Claw 1: Attack: 14 Damage: 10 slashing damage + 3 necrotic damage
Claw 2: Attack: 25 Damage: 11 slashing damage + 8 necrotic damage
Also, Brother Siegfried, since you are within 5 feet of the troll at the end of your turn, you take 9 necrotic damage, unless you make a DC 13 Constitution save, in which case you take half damage.

Vandeyr keeps up the assault, waving his hand to direct the flaming sphere to bash the troll on Siegfried, then launching a fire bolt, laced with more of the sulfur and brimstone that emits from his spells. 

Flaming sphere deals 11 fire damage, half on a successful DC 16 dex save

Fire bolt Attack: 15 Damage: 9 

Sigi CON save: 12

Sigi Concentration Check: 14

Standing within the circle of dancing spirits, Brother Siegfried is protected from all harm.  The troll's teeth and claws crash upon his armor and shield like waves upon granite cliffs.  Even its foul odour barely fazes the cleric.  He holds tight to his amulet and maintains the spell of protective retribution.

Rawlings watches as the other troll is taken down by the other swords.  She nods in approval and reaches out towards the remaining troll again and sends her eldritch blasts toward the towering creature.

Attack: 14 Damage: 10

Attack: 22 Damage: 7

Dex save vs flaming sphere: 18

The rotting troll attempts to step out of the way of the flaming sphere, but doesn't avoid it entirely. And in doing so, steps right into Vandeyr's fire bolt that burns deeply into the monster's flesh. Both fires burn with a sulfurous smell that is almost hidden under the smell of the troll itself.

Almost simultaneously, Rawlings' eldritch blasts slam into the creature, carving through its already damaged hide.

Tor and then Brother Siegfried's turn.

One troll reduced to a stinking pile of flesh by the Brother's spectral famers, the other repeatedly sliced and burned. This fight was turning in their favour. Time to try to finish it.

Tor approaches the last troll, maul in hand. He grips it tight with both hands, and swings with all his might, determined to bring this thing down.

1. Maul: 23 Damage: 10
2. Maul: 21 Damage: 14

Tor steps forward to the wounded troll. In one swing, he crushes the things knee-cap. It drops down, barely holding itself up with its massive arms. Its roar of pain is cut short by Tor's second swing that crushes its skull, sending bits of brain, ichor, and blood spraying. 

(That's all the visible threats, so we can drop out of combat.)

After the rush of battle and the roar of trolls, the sudden silence in the Mere is unsettling.

Vandeyr huffs a few moments as the adrenaline eases its way out. "Hello? Anyone there?" 

He looks around the troll fire for signs of captives 

Investigation 27 

Tor wipes a lump of grey matter from his cheek with a grimace. Even their brains smelled rotten.

As Vandeyr looks for survivors here, Tor examines the ground to make sure the tracks they were following continue.

5

Vandeyr hears no answer. There doesn't appear to be anyone present aside from the trolls and the body of the dead lizardfolk. The corpse itself is mangled and hard to look at for any but the most hardened adventurers.

Nevertheless, Vandeyr can tell the lizardfolk was likely a scout, judging by the mud covering its scales (where they haven't been chewed off by the trolls) in camouflaging patterns, and how the jewelry and body piercings common among lizardfolk in this area have been tied up and wrapped with leather and string. Lying a few yards off, the lizardfolk's bag sits.

As a skilled alchemist, Vandeyr also recognizes that troll skin can be used in a number of potions. Typically, they would be used in regenerative, healing potions, but these trolls' skins would likely make a strong ingredient for an offensive potion or spell.

Tor, meanwhile, is able to follow the lizardfolk's trail leading back a couple hundred feet in the general direction the party came where it had broken off from the larger trail the party had been following.

Vandeyr is tempted enough by the troll skin to make a rough job of hacking some off quickly, but doesn't waste time. Minutes may count for something in this chase.

Quote from nschrock >>

Vandeyr is tempted enough by the troll skin to make a rough job of hacking some off quickly, but doesn't waste time. Minutes may count for something in this chase.

 (Give me a Wisdom check + proficiency modifier to represent your use of Alchemical Tools)