Hey Thanks for the reply!
I've considered going mono-black, but the two multicolor cards (the only ones which actually needs white) help the mimic transform (and are nice with the edge) and also provide extort, which is somewhat the theme of the deck.
Of course removing the white cards would help the manabase mostly, by assuring a turn one untapped land, although there's not much to be done on turn one except the nip. In my experience the deck starts casting spells on turn two consistently, and the loss of a turn-one mana is affordable. consider the two multicolor cards are nice creature too.
In any case, what would you add instead of those 8 cards (I take the suggestion of the removal as replacement for the
unmake and snuff-out, am I right?)