Like I said in chat:
This card costs the same as cloak for 50% of the effect. However, 50% is enough to discourage players from using PC unless necessary, making this more valuable than half of cloak. I suggest a -1 cost to both unupgraded and upgraded.
I agree that a cost reduction wouldn't hurt, that may be another avenue for cross synergy (costs one less if your mark is the right type).
--E.g. make air with cost reduction of 1 if your mark is water or keep water with a cost reduction of 1 if your mark is air.
But I do think it is definitely different enough from cloak to warrant a new card.
Cloak encourages AE spells (which bypass and often dispel cloak)
This card deters AE spells since there will be a 50% miss chance
I think thats enough right there to consider it a unique mechanic.
(I see some definite synergy potential with unupped pandemonium since it would give your own creatures a better chance of survival)