Mana obelisk. I'll check which expansion.
It cancels mana trickery.
It's Mana Prism. You are mixing it up with Mordok's Obelisk and creating a card name that doesn't exist...
It doesn't help though because you are being mana denied, and then make the problem worse by paying another 7 mana to slowly get your mana back over time. When I play mana denial mana prism is the card I most want my opponent to play.
An anti-mana denial card would have to be almost free, and trade another resource (eg: life) for mana to be good. And it doesn't help against Mana Siphon which is one of the main mana denial cards...
