Thieving Mindbreak

Spells you don't own cost {1} less to cast for each corruption counter on Thieving Mindbreak.
{1}{b}{r}, put a corruption counter on Thieving
Mindbreak: Target creature you control heists
and gains your choice of haste or +1/+1 until end
of turn. (To heist, look at the top card of target
opponent's library. You may cast that card and spend
mana as though it were mana of any type to cast that
spell. If you don't, you may put that card into its
owner's graveyard.)