Alex, The Swindling Maestro

Alex, The Swindler is unblockable.
Rogues you cast cost {1} less to cast for each
permanent you control but don't own.
{u}{b/r},{t}:Exile a creature or artifact from a
graveyard. As long as it is exiled, you may cast
that card and spend mana as though it were
mana of any color to cast that spell.