Alone against all

Can't be countered
Haste, Horsemanship, Double Strike, Hexproof
Eminence As long as this creature is in
the command zone or on the battlefield, counter
every opponent spell.
This card cost {1} less to cast for each card in
your hand. If this creature kills an opponent,
untap it and there is an additional attack step after
this phase. If this creature leave the battlefield,
instead return it to the battlefield with a +1/+1 counter on it.