Make Tenacity Stop Certain Knockups

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don't have*, and why would I NEED specific knowledge?

Because you'd need to know exactly which knockups are 100% countered by tenacity and which are unaffected. It'd be annoying as crap

1. because you'd have to memorize every single case
2. because it makes any form of tenacity remove one if not all of a champions CC.

{quoted}

don't have*, and why would I NEED specific knowledge?

Because if Sej's knockup is reduced by tenacity but Cho'Gath is not then people will either not itemize for Sej or itemize incorrectly for Cho'Gath.

You shouldn't have to know specific cases for stuff unless you are extensively playing that champion. Counterplay should be general in knowledge.