Braum's Q and magic pen

Greeting summoners,

Curious if we know if Braum's Q is affected by magic pen? It says, "Braum propels ice from his shield that travels forward in a line, dealing magic damage to the first enemy hit, applying Concussive Blows and slowing them by 70%. The slow decays over 2 seconds." yet, after building a Liandry's Torment to test the increase in damage, it felt like only the health was a factor for increase in damage... thoughts?

Cheers, Summoner BOOYA SHAMBO