The new Conqueror will give champions 30 AP-50 AP and 10 AD-30 AD once fully stacked. The healing will be mitigated by armor/MR which isn’t a really big problem for AP champions if they go Void Stuff.
But the major problem is not all mages will be able to use it because they stack it slowly, but something like Casssiopeia will stack it in no time. Other champion like Sylas, Mordekaiser will shine from this rune as well.
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With the new conqueror changes some might say that riot is bringing back Tank meta as it does not give true damage anymore. But many AP bruiser champion may shine with that extra 30-50 AP and 15% heal. New conqueror might still be run by AD bruisers like Riven, Kled or Aatrox for that healing only.