Bane, The Strife Emperor

When Bane, The Strife Emperor enter the
battlefield, you become the monarch.
As long as you are the monarch, spells you cast cost
{1} less to cast. If you are not, creatures you control
have double strike and trample.
You may return Bane, The Strife Emperor from
your graveyard to your hand by exiling the top of
your library until you exile cards with mana value
10 or more.