Argyle King
Legend
Yoda
Yoda
I take Encounter to mean wandering monster or creature in their lair? Environmental challenges, tricks, traps, and such are usually treated differently. Navigating in a swamp is a trial in and of itself. Add in constant portaging, insects, fetid water, hot temperatures - and those are best case scenarios - and you get a difficult journey for your players to deal with. Swamps are not low level territories.
For creatures think about: Swamp nixies, swamp nymphs, water weirds, catoblepas, lizardfolk, swamp kaolinth (aquatic hobgoblins), swamp Kopoacinth (aquatic gargoyles - flippers, not wings), water nagas, giant otters (I *think* are intelligent), and pirates.
Swinging vines to help avoid rolling logs, alligators, scorpions, pits, and quicksand.
Sure, he's a crazy goblin psion who uses telekinesis to pull the PCs ship from the swamp it sunk into. Once the ship is out and drained, they can patch a whole and go on to rescue a couple friendly NPCs who may or may not be bait.
At which point the DM reveals to the party paladin that the BBEG is his father.
When the ghost of his mentor shows up to offer advice, is the paladin required to turn him?