pull a rabbit out of a hat

(idiomatic) To do something surprising or beneficial.

Example: 2014, Michael White, "Roll up, roll up! The Amazing Salmond will show a Scotland you won't believe", The Guardian, 8 September 2014:
  But Salmond the magician's dazzle has not pulled those crucial rabbits out of his hat. Not on tax and spending, on the currency union which he wants (but rUK does not), on Scotland's relations with an EU which does not want this aggro.