WHY ITS NEAR IMPOSSIBLE FOR MALZAHAR TO KILL RIFT HERALD

I just played Malzahar. He's OP. Solo everything in jungle. EXCEPT Rift Herald. Why? Not because of damage, but because if you use voidlings to tank, rift herald has to constantly switch targets, resulting in loss of agro and instant healing. Yes, its technically still possible if you manage to outdamage his reset healing and constantly reagro him, but for all intents and purposes its near impossible to solo, when he can solo baron/dragon.

Am I asking for buffs? Not really. Just pointing out something amusing about our new OP mage.