just for precautions i think you may want to look into a card called leyline of the void. its sort of a safety net if you are not relying on the opponents graveyard. it makes all cards that would enter their graveyard be exiled so there is no flashback or shuffling back in or anything of the sort.
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you should find someway to increase mana ramping a bit more and find some lands that dont tap when they enter. but i think the high mana cost is a non issue here
powerful looking deck dude!