With all the mana-related tweaks going on in PBE, what about Mana Burn?

I remember back when Wit's End used to burn mana, but the effect was removed because it was strong against tanks, not mages, by rendering them OOM too easily and thus making them useless. That was years ago, though, and out of curiosity I have to wonder if there is a way that Mana Burn could be reintroduced into the game as an anti-mage effect (but not anti-tank).

I sincerely doubt Riot will bring back Mana Burn due to it being classified as toxic gameplay, but just to humor the idea for a moment, here are a few things I'd do if I were to bring back Mana Burn.

• Mana Burn would only come from an active item effect, so it's gated by cooldown and by a purchase decision.
• Mana Burn would not burn flat amounts, but would burn based on a target's current mana. This would make it highly ineffective against targets that are already low on mana or who don't have much, but strong against high-mana targets (i.e. someone with an ).
• Mana Burn's effectiveness would be reduced by enemy resistances (i.e. high AR or MR would reduce its potency, so again it would fizzle against tanks).

Again, Mana Burn is probably gone for good. I'm just theorycrafting here.