While standing on a chest (or item, not sure which yet), and firing the Cluster Launcher, it will immediately detonate and injure the player.
The player can still shoot over the item normally if they are not standing on it.
Save with cluster launcher equipped should be attached. Simply stand over the item on the ground and fire.
(Uploaded to Mantis, reposted here just in case)
http://www.arcengames.com/mantisbt/view.php?id=18147
