I love the idea; the card is quite creative, but it's really overpowered. Trust me, I'd break the game in half if I got my hands on this :p I could make control decks that would be nearly impossible to beat. If anyone's played against the 60 card light mark stall in BL this season, imagine that with a few of these in it... it would be -really- strong.
Perhaps this card could have some sort of timer on it, much as wings, dimshield, and sundial do. That would still have the card be quite strong, but it would keep it in line with other card advantage like hourglass or mindgate. The lantern draws for free (assuming the quanta threshold is met, which it probably will be) but, with my suggestion, would not last forever, maybe something like 3 turns, before it 'burns out'.