If Malz was reverted assassins would have a counter again
Title. The main reason I loved Malzahar (pre-rework anyway) is because he was always a mage that was a solid pick against any assassin.
I think the main reason why assassins are running rampant is because there is nobody from the class that they counter that counters them (if that makes any sense). It's genuinely accepted that most assassins counter most mages (save for maybe Vladimir and Heimer who have safe play styles), but Malzahar was always the mage that was known as the true assassin killer.