When I tried out hope in the trainer it capped at 6 when I had at least 10 light emmiting creatures on the field... if this card also had such a cap it would be rediculously weak.
Furthermore, hope/RoL/Fractal decks are increadably weak to creature control, one Oty on you and you're dead. The same would apply to this card.
However I do like the idea of purge.