Flamestrike
Legend
I'll have the rogue and my familiar check out the area to make sure there are no ambushes.
The Rogue and Raven both roll Perception with disadvantage due to low light (Passive Perception 18 on the Rogue though, so that's his 'floor') because neither of them have Darkvision (which its that dark already would still likely be at disadvantage anyway) and they cant see much on the other side of the river anyway (its like 50' across).
After a quick scout of this side of the bank, and a fly over they report nothing, but the Rogue lets you know it looks like something (or somethings?) BIG have damaged the bridge; he did notice claw marks on the edge.
Otherwise the area looks all clear.
Assuming the coast is clear, my Wizard will use misty step to cross the 30' hole on the bridge. We will have the team throw me some ropes and I will tie them off and give them a quicky bridge to cross.
You misty step over to the other side, and call the Fighter over to toss you a rope, which he does.
The wizard will smirk as he works, noting "Sorry Mac (the fighter), I still have the long jump record".
As you turn to the Fighter, you see a look of horror cross his face, as a blood curdling cacophony of bellowing and roaring comes up from behind you. Turning around, you see two Cave Trolls (Stealth +4, Advantage from hiding in Rocky terrain, total result = 19!) have emerged from hiding spots in the rocks on the other side of the bridge; they're 20' away from you, and charging at you at a great rate of knots!
Roll initiative. You're surprised on round 1 (as is everyone else, barring the Scout Rogue, who has the Alert feat).
You're alone on the Trolls side of the bridge, but you have tied the rope up.
(I know you might think Im making this one up, but this is legit the encounter! @tetrasodium can verify!)