Essendrum sighs and says to the woman, “Well, are you here to help or not?  I temporarily clouded the mind of a second giant but he may return.  I suggest you decide what you’re going to do quickly.  I am tired and do not wield a sword well.”

Kiza rushes off to help with the fires close by.
Bjorn seems deep in prayer for a moment.
Essendrum, Spike, and Enoch stand around the burning body of the Fire Giant. Essendrum and Enoch try to cover the fire with dirt while Spike tries to push it over with his foot.
(Need a Strength check at Dis. from Spike if that is his current course of action.) 

"You have never fought Magmin before have you?" the newcomer asks, a bit amused. "Their initial burst is hard to put out. I haven't found anything that can do it outside of magic. If you give it a moment the flames should die and you'll be able to put the rest of it out but..." 
She pauses for a moment then says. 
"I am not sure why but that fire giant is burning from the inside. Interesting!"

The woman walks to where the hole is in the middle of the campground and looks inside. After a moment she asks:
"Did any of you see what he took out?"

People are running to and fro in the area. Finally, a bucket brigade has started, with Kiza's help and they start dousing the fires nearby. 
Others have shovels and are digging as fast as they can and throwing dirt everywhere there is fire &/or smoke. 

Quote from LafcadiotheLion >>

Essendrum sighs and says to the woman, “Well, are you here to help or not?  I temporarily clouded the mind of a second giant but he may return.  I suggest you decide what you’re going to do quickly.  I am tired and do not wield a sword well.”

 The woman doesn't respond to Essendrum's outburst. She continues to inspect the hole. 
A man comes running up to her. His face is black from soot and he is a bit disheveled.
"My Lord," the man says. "Scouts report the raiders have all moved to the north." 
She just nods. 

Spike:

Strength check at disadvantage:  6

(( I figure we're probably not going to get into combat again in the next several minutes, but just in case, I forgot that Enoch needs to make concentration saves for keeping up his Shield of Faith spell:

CON Save vs. DC 10:9
CON Save vs. DC 10:20
CON Save vs. DC 10:15 ))

Essendrum sends his raven up to 90 feet to give him advanced warning if the other giant returns.

“No, we did not see it.  This giant appears to have been a sorcerer willing to summon dark magic to keep his secret.”

With that, Essendrum sets about a ritual casting of Alarm on the remains of the giant’s body, limiting the triggers to giants, orcs, and Magmin and with a mental warning.  It will take roughly as long as the Prayer of Healing spell Bjorn is casting.

Spike:

”This big one had it with him just a moment ago—whatever he dug up,” says Spike, working harder at turning over the dead Giant if his first attempt fails.

(( Enoch continues shoveling until all nearby flames are put out. He eyes the "lord" who had first spoken to them, but says nothing for the moment. ))

prayer of healing result: 15

Everyone is healed 13 hit points.

Enoch continued to work, but glanced at Bjorn as he uttered his incantation. It was then he felt a healing magic remove his wounds. Pausing his shoveling for just a moment, the paladin nodded at the sea elf. "Cleric, right?" he said. "Thanks. My name's Enoch. I'd shake your hand but, well, fire first." The young man grinned wryly at his own quip as he resumed his task.

Spike fails to move the giant's body.
Over the course of several minutes, and efforts from the group, the flames over the giant's body subside. The Lord of Triboar, one Darathra Shendrel, as the group comes to understand who she is, moves up and stands next to the party as those who are trying to put the flames out work. 
Meanwhile, Bjorn has moved close by, kneels, and begins to chant and pray. After he is done those injured in the group feel a bit better than they had.
Essendrum sends his raven up to act as an aerial guard and finishes his Alarm over the giant's body.  
It is Essendrum who sees the object first after the flames die out over the Giant's body. There is a pouch that has burnt almost through on the Giant's belt. An odd-shaped stone can be seen inside.  It looks to be some gray-colored stone with azure streaks running across it. 
Everyone gathers around and looks at the thing.

"What do you suppose it is?" can be heard coming from one of Dara's men. 

Dara looks to the party and then to Essendrum. "You said you think the Giant was some sort of Sorcerer, right?" she asks. "Is there magic lingering on the stone Mage?"

Having completed his Alarm spell, Essendrum bows to Lord Darathra, “Your ladyship is wise not to touch it just yet.  Permit me to cast a ritual of detection and we shall know.”

Essendrum casts Detect Magic as a ritual.

The party and Dara wait as Essendrum performs the proper rituals. 
He closes his eyes and seems deep in thought as he mutters the arcane words over and over again. His at one moment his hands are a flurry of movement and he raises his voice and says a single arcane word.
Essendrum opens his eyes. The telltale blue and green light of arcane energies causes his vision to swirl. Essendrum takes a deep breath and focuses his mind. His vision becomes keenly sharper.
Essendrum sees small arcane energies emanating from those around him, mostly from objects people have in hand or are wearing. He casts his eyes upon the giant's body and the stone. The stone is bathed in the blue-green arcane energy but, there is a darker energy that surrounds it as well. 

Essendrum’s Mage Hand holds the stone before the lady.

“This stone they sought does indeed have dark magic about it.  I cannot say whether the pall of death that hangs over it is but a momentary spell cast by the giant, or a deeper evil.”

Essendrum turns to Enoch.

”Perhaps Sir Enoch may sense something.”

The old wizard makes a few notes in his grimoire..  

“Barring that, I suggest we lock it away without touching it.  Tomorrow I can attempt to purify any temporary spell and we can see what effect that may have.  I am afraid I am exhausted from the morning’s heroics and can do little more today.  If you have any records in your keep I would be glad to examine them for a hint of who might have buried this stone here.  Perhaps you had a passing caravan of giants in the last week who wielded shovels?”

Enoch blinked, somewhat taken aback at being asked to assist, but then quickly nodded stoically and stepped forward. He'd been acting as a paladin for a while, but it still caught him off guard when others treated him as he would have thought befitting a cleric. True, he had the power to sense evil now, but it sometimes still surprised (and humbled) him that others would actually rely on him to make use of it.

The young man extended a hand towards the stone without touching it, and closed his eyes. Tapping into his own inner conviction, powered by the binding of his oath, he turned his mind toward the spiritual realm, and sought out the evils nearby.

Enoch will spend an action to activate his Divine Sense. Until the end of his next turn, he can sense anything affected by the Hallow spell or know the location of any celestial, fiend or undead within 60 ft. that is not behind total cover. (Full description in spoiler below.)

The presence of strong evil registers on your senses like a noxious odor, and powerful good rings like heavenly music in your ears. As an action, you can open your awareness to detect such forces. Until the end of your next turn, you know the location of any celestial, fiend, or undead within 60 feet of you that is not behind total cover. You know the type (celestial, fiend, or undead) of any being whose presence you sense, but not its identity (the vampire Count Strahd von Zarovich, for instance). Within the same radius, you also detect the presence of any place or object that has been consecrated or desecrated, as with the hallow spell.

 

Kiza sighs with relief upon her wounds being healed and then quietly listens as she stares at the object dug up by the Giant "A rest would be welcomed, though I wonder what is that magic rock"

Bjorn speaks up, "There is an option we can try. I have a spell that lets me speak with the dead, but I don't speak Giant.  Essendrum can tell me phonetically the questions to ask it.  He can listen to each of its responses and have me repeat his additional questions, for a total of 5."

Bjorn then mutters a few mystic bits and suddenly is replaced with an image of plain looking human.

"And I am able get around the problem with asking it questions by those who killed it.  You want to do this, Essendrum?"

“That could be most instructive!”

Essendrum writes down what questions Bjorn proposes in Giant so that he can read them to Bjorn when the spell is cast. 

Spike:

Watching the proceedings with interest, Spike remains silent—this talk of magic and speaking with the dead was certainly out of his wheelhouse, but it could give them some hint as to what is going on.  He did, however, feel some satisfaction that he played a key role in keeping the Giant from escaping with its prize, whatever that magic rock was for…