User blog comment:Supafrunk/Mana-Regen Based Champion/@comment-24.190.81.23-20121025042913

First, removing mana from an enemy is useless against Energy/manaless champs. That's why Wit's End no longer burns mana.

Also, thought it would be an interesting idea if, like Shyvana's ult, that the mana was burned at a very high rate, and then gave a constant effect over that time, such as 200% damage while all abilites cost that much more.