Talk:Garen/@comment-8471952-20130420212938/@comment-4834593-20130507065631

" Unique Passive: Dealing spell damage applies a damage-over-time effect (...)".

Nowhere it says it has to be magical damage, so it procs on all spell damage, be it physical, magical or true damage.

I still wouldn't recommend it for serious games though, as you're just wasting the AP and only using the mpen on ult.