Totally Not GG
Scout by Air: This bog is thick, murky, and mostly uninhabited, Perception DC 20: Something very large is moving in the swamp. DC 15 Survival notices quicksand, failure results in getting caught in quicksand.
Scout by Land: Perception DC 20: large tracks in the swamp match two separate, massive creatures (followup DC 20 survival identifies one as a dragon, and a 25 identifies the other as a froghemoth.
This one’s straightforward as fuck. A froghemoth comes charging through the underbrush at the PCs! Weirdly, though, this froghemoth is moving much more slowly than it usually does, swimming through the muck at a base speed of 15 feet.
Froghemoth moving at half-speed (1): http://www.d20pfsrd.com/bestiary/monster-listings/aberrations/froghemoth
Inside the froghemoth is the source of its torment: a stone of weight. However, inside it is also a belt of teeth, furthering its torment; a +1 adamantine breastplate with armor spikes, which has driven it positively nutty; and six Adamantine Shuriken lodged in its digestive tract, which have rendered the creature’s life positively unbearable.