Not to be confused with Plaguing Hulk
The Slekeleon is a Special Enemy. He is the mini-boss variant of the skeletons, frequently found in the Chaos Expeditions, Onslaught and Incursions maps. The Slekeleon respawns at the beginning of every wave after he is first killed in the same spot he is killed in the previous wave. He has slow movement speed and melee attack speed but his attacks have a very large cleave area. Notably, he seems to have a higher than normal resistance to stuns.
Since the Slekeleon is slow and has slow attacks he can be baited into swinging then the player can back up making him miss, though he can still become a threat if left to break through your defenses. Due to respawning at his death location each time, you can prepare by setting extra defenses or gather up your team to quickly focus him down. As a miniboss he has a very high amount of health.