A large portion of relevant modules/templates have now been switched to cargo. Various usages of SMW throughout the wiki need to be replaced by the new functions, in particular item tables. If some pages do not show up but contain no errors, please null-edit them. To see how you can help with the port check out Path_of_Exile_Wiki:To-do_list/SMW_migration (and leave a comment on the talk page if you have questions).
Overwhelm is a notable Ascendancy passive skill for the Slayer that grants increased stun duration against enemies and immunity against stun. It also guarantees a stun against enemies on full life and a chance to double stun duration.
Overwhelm does not cause a hit to stun enemies at full life if it does not deal any damage.