At last, Benjamin had to stop his exploration, mainly due to the lack of space in his backpack.
In the beginning, he had only flown north; no matter what kind of undead creature they encountered, he would kill them and retrieve their corpse so that they could perform further research on it in the academy. Now, after exploring for more than half the day, they left the wilderness and flew into a boundless swampland.
Each time they got close to the swamp, undead creatures would crawl out from the muddy ground and glare at them ferociously. Perhaps this was the instinctive hate that the dead felt towards the living that is so often mentioned in myths and legends.
As for the variety of undead creatures, Benjamin still could not figure out anything about them.