"Whenever a player's mana pool empties, if it was not caused by a spell or effect, Vulcanologist deals 1 damage to that player for each point of mana that was emptied. (Each player's mana pool empties at the end of each step and phase)"
How about the above? Works more like mana burn did originally, since it doesn't trigger off stuff like Omnath or Upwelling (and still doesn't trigger off Mana Short). I suppose making this guy Legendary would be even more true to the old function, but I think it's cooler being able to play multiples.
I don't like restricting the possibilities of the card. Using mana short to burn someone is a very awesome application of the card. Its a bit like price of progress
I'm just trying to stick to the stated intent. As a card that essentially brings back mana burn, I was trying to match the old functionality as closely as possible. If we're just talking about the card in a vaccum, I totally agree that this plus Mana Short is a really cool interaction.