Depends where your portal is. If it's deep inside the swamps it's gonna be hard but if you have it near the border of the swamp all you have to do is grab some stamina food where you spawn, use the 1st boss power and go through the portal, find a troll in the black forest nearby and bait it into the enemies of the swamp (trolls can even kill abominations).

Or you can simply make the run for it dodging as many enemies as possible if you don't see any trolls near. With the power of the deer active you won't get winded in a while.