Essendrum takes the wand and examines the body, assuming it doesn’t leap up and try to throttle him.

Investigation: 12

The body does nothing as Essendrum takes the wand from its hand.
The elf is dead, though you are not sure for how long.
You look over the body and the things the dead elf was carrying.
You only find his wand, robes, and a few coins (6 gp 7 sp) in a small pouch & his spell component pouch. From the contents inside the spell component pouch, you surmise he was a novice in the art. 
On the pouch and inside the collar of the robes,  you find an embroidered RS in purple and gold letters. 
Essendrum:

If nothing else seems interesting on the island and Spike is ready to ferry Essendrum across, he will pocket the coins and head back.  The magic wand will have to wait for a rest to be attuned.

DM:
Assuming Spike does ferry Essendrum back to the group, (Athletics Roll), what are the group's next moves?

(( Once they're back, Enoch will just suggest we go back to the path that Spike had suggested earlier, to try to see if the trail we were following reappears. ))

Spike:

Doing his best to secure the rope this time, Spike carries Essendrum back over to the platform.

Athletics:  14

"Yeah, lets back track and try that other corridor." says Kiza glad Essendrum and Spike are safe and did not fall. 

6

The party gathers together and makes their way up the steps and across the bridge, back into the main hallway. 
Traveling north you come to the intersection from before and take the passage to the right. 
The hall goes 65 ft. to the east then turns north. 
As you start to make your way down this hallway you hear the thundering sound of flowing water. 
About 40 ft. down the hallway the walls have fallen away and you find yourself standing at the edge of a small cavern, approximately 50 ft. wide. The floor has become a stone footpath that leads across the middle of the cavern whose eastern and western walls are obscured by waterfalls. The water appears to be coming from two cracks at the top of the east and west walls and falls some 40 ft. into the rushing waters of a river below. The air is cool and damp and there is a layer of water that covers the footpath. 
Across from you, some 25 ft. north, you see the footpath connects to another hallway.

 Actions?

Enoch eyed the footpath suspiciously. "Best to take it slowly across this walkway," he suggested. "In fact, it's probably overkill, but just in case...."

The paladin spoke a quick prayer as he extended his palm towards Essendrum and Kiza, then placed it on his own chest. Spell cast, he then turned to Spike with a shrug and a sheepish grin.

"I figured you wouldn't need it, considering you can fly over.

"As for the rest of you," he continued, "if you want to cross first, I can concentrate on the spell assisting you while you do. I can take up the rear."

Enoch casts Bless, targeting himself, Essendrum and Kiza. When making saving throws, we each can add 1d4 to the roll.

Essendrum looks down to see he still has the rope tied to his waist like a belt.  He untucks the long end and gives it to Flint.

”I’m looking forward to my week in the library,” grumbles the wizard.

Acrobatics: 4

Spike:

"Give me a moment first," says Spike, and he proceeds to fly over and check out the walkway/bridge for structural stability, flying over, under, and around it as reasonable to check it out.

Perception for anything dangerous hiding:  21

Stonecunning:  Unable to parse dice roll.

Once Spike gives the ok Kiza will attempt to cross. 

Acrobatics 

13

Spike starts flying over the bridge. Suddenly he sees movement coming from the right side, beneath the waterfall. Leaping from the waterfall, onto the bridge are 6 Troglodyte ready to fight.

Initiative: 
Trog group initiative: 11

Initiative 18

Spike Initiative:  7

Enoch's Initiative: 14

Kiza initiative 

17

Because it appears Essendrum can incinerate all six without harming Flint or the water-soaked terrain, and since Essendrum very much does not want a Troglodyte grabbing someone and leaping into the waterfall, he casts Fireball.

31  fire damage. DC 17 save for half.

Essendrum steps forward and casts his spell.
The fire forms in front of the mage then rockets forward and explodes, taking in all the Troglodytes. The explosive is massive and the creatures are thrown from the bridge, mostly in burning pieces.
However, with Spike initiating the Troglodytes by flying over the investigate, he is also caught within a small portion of the blast.
Save and take 1/4 of the damage. Fail and take 1/2.

Actions?