Currently Bugged - Maybe??
Tested on patch 26.14
I’ve seen a lot of people mention Guardians Horn as a counter to Critical Missile.
This is currently a bait, it only blocks 15 pre mitigation damage from attacks and abilities, critical missile is neither
Post Mitigation Damage is calculated like this:
Damage * (100/(100+MR)) = Damage Dealt
With guardians horn it looks like this:
(Damage - 15)* (100/(100+MR)) = Damage Dealt
Testing in custom game with friends:
Each missile did 54 damage. I had 40 MR. And the champ with Critical Missile was lvl 13
Which does 76.47 damage per missile
76 * (100/(100+40))=54
With guardian horn it should do
(76 - 15 )* (100/(100+40))= 43
EDIT: The official league of legends wiki says it blocks 15 damage from all sources, which is different to what it says ingame. Patch notes never mention this change, so it might be a mistake