i have tons of experience with that combo, i have played it for years.
if you really want
mindcrank to work in modern you need to consider some Cards:
going with the duskmantle line, you need to consider getting
aether vial so that you can put the mage into play Instant speed.
T1:
island + vial, T2:
swamp +
mindcrank, T3: play a 3rd land. and pass the turn. in response to anything that will send a card to his graveyard, you use the vial to enter the
duskmantle guildmage, and activate his ability with Your 3 mana.
you can also consider to add a copy of
necrotic ooze wich will act as a 5th guildmage and will allow you to avoid a
pithing needle on Your mage.
mindcrank alone is a bad card in modern. (spending 2 mana to play a card that has zero impact on the Board)
to get more out of
mindcrank, add
bloodchief Ascension to Your deck. with 3 Counters it will basicly save you the trouble of playing the guildmage and activating it. Also consider
reshape to trade an
aether vial to find
mindcrank for you.
trophy mage can also be considered.
i would get rid of most of Your other mill Cards like
mind grind,
mind sculpt,
consuming aberration,
curse of the bloody tome,
psychic strike, and focus more on protecting Your combo by attacking opponents hand with discard, or destroying his permanents. counterspells also sends Cards to the yard. (
countersquall)
there are several other ways to build the deck by adding another color.
adding green for
abrupt decay,
collected company,
Savage summoning could work.
adding white for
ojutai's command and some hatebears could also work.
adding red will do a lot with
bloodchief Ascension,
Lightning bolt,
volt charge,
trash for treasure,
kolaghan's command comes to mind.
as for the sideboard i would use
yahenni's expertise instead of
languish, and
surgical extraction and some ways to deal with the few Cards that actually destroy the combo like
rest in Peace.
some modern decks without Access to white mana has no way to deal with
norn's annex and that is pretty sweet if you have
bloodchief Ascension out.
have fun with the cool combo!