The dwarf's breathing evens out and his eyes flutter open, "wha... safe? No, no, run!" he gasps. Jon instinctively turns to follow the terrified dwarf's gaze, just in time to see the bloated abdomen and trailing legs of an enormous arachnid disappear up over the other side of the bridge.
The other get a front row view as the huge invertebrate effortlessly contorts itself to fit through the bridge's scaffolding and hauls itself up on the deck with a scrabble of chitin on wood.
"That's a biggun," intones the deputy flatly.
Know (Nature) DC 15
SpoilerThe hauntly humanoid aspect of the spider's face identifies it as an Ogre spider. Despite its enormous size, it's actually quite adept at folding itself up to fit in surprisingly tight spaces. It goes without saying that it possesses a potent poison which weakens and incapacitates its victims.
Map & initiative
SpoilerThe spider used it surprise round to climb up the bridge, so its full rounds from here on out. Mika first, then the spider, then everyone else. The deputy will go after the last group member to keep things simple. The dwarf is still too weak to move, but strong enough to hold on to his perch securely.
Purple = Jon is about 10 feet below bridge deck level. Climbing speed is 1/4 move speed, or 1/2 if you take a +5 DC. You can also move sideways at the same speeds.
Remember, the spider has 15' reach.
Mika is up, 24 hours.