Kayn's ult ignores tethers when no other ability similar to it does this
Similar abilities: Any untargetable effect, Zed ult, Yi's Q, Shaco's ult, Zhonyas.
Spellshields also do not block the activation effect of a tether.
None of these ignore tether effects, but Kayn's ult for some inexplicable reason, does.
This isn't intuitive and runs counter to all the prior knowledge of similar abilities vs tether effects. It also makes him inordinately powerful vs champions with tethers. Namely, Leblanc, Karma, and Nocturne. It's a silly, unusual, singular interaction for Kayn only.