You could swap the black for red and play Nahiri, the Harbinger as an additional way to cheat in Emrakul

Seems very nice, but I'd do some changes: first of all I would change Cast Down into Fatal Push. Then, if it's on budget, I'd increase the numer of Polluted Delta, Flooded Strand and Marsh Flats and I'd cut Nimbus Maze and River of Tears. I'd add also the schocklands, if on budget: Hallowed Fountain, Watery Grave and Godless Shrine, cutting Adarkar Wastes and Underground River. Then, why not a Logic Knot or Mana Leak instead of Negate and Pact of Negation? Also, since you have decided to use only 2x Inquisition of Kozilek, couldn't be better Thoughtseize? Another 2 token spawners I would take in consideration here are: Bitterblossom and Secure the Wastes (since is instant and creates as many tokens you want). Another thing: since you have only 4 black spells, why won't you consider cutting all black from the deck?

Thanks for the suggestions, surely the manabase is easy ti upgrade with shock and fetch lands. Bitterblossom is interessing but way top out of budget. Secure the Wastes is good, It night replace lingering souls. Thoughtseize is something I've considered bit it's a bit out of budget at the moment, bit still in the possibility list. I love splashing black for more interactivity with the opponent and because of hand-hate and cheap removal. Nahiri, the Harbinger is Cool bit I think that in order ti play her i Need to play almost a different deck. Thanks for suggestions, i'll keep those in consideration

Not sure if it's in budget or not, but Blinkmoth Nexus shines in polymorph decks. It can turn itself into a creature for Polymorph

Blinkmoth Nexus is Cool! I was also considerino Boseiju, Who Shelters All, May It Be a good idea?