there are much better mana rocks than
grixis obelisk.
vision skeins just isnt a good card with the amount of card draw u have. i dont think
library of leng is very good. targeted removal like
terminate and
dreadbore isnt great in edh, and i would suggest swapping them for another board wipe and
chaos warp. i think
bloodchief ascension is slow and if u dont have it, pricey to buy. is kess really necessary? id run something like archaomancer cause its cheaper (price wise), or maybe
the mirari conjecture for the amount of value. Also, creatures r fragile. kami is gonna be hard to consistently cast on turn two,
fell specter is just a worse version of something you already have a lot of.
whispering madness is bad because you run very few creatures.
price of knowledge is overpriced (mana wise), not very good, remember, u are essentially an "aggro" deck.
counterspell being double blue is something to think about, i suggest also running
mana confluence, just great value. niv mizzet is just bad. dont run him (no offense).
psychosis crawler is good cause u basically do 3 damage per draw, since it deals 1 to ALL opponents. since u r very low on creatures, u should run
evacuation and stuff like
devastation tide in addition to
cyclonic rift to slow ur opponents.
breathstealer's crypt is good cause of the amount of creatures u run. u only have like 5 red permanents beside nekusar that turn on the
kederekt parasite, so u should prob take that out.
cruel ultimatum just doesnt give you that much value for the mana cost.