Ride of the Rohirrim

Whenever a Rider creature you control attacks
tap target creature defending player controls.
Rider Creatures you control get +X/+X were X
is the number of mounts you control.
"Forth and fear no Darkness. Arise, arise
riders of Theoden! Spears shall be shaken,
shields shall be splintered, a sword day, a red
day ere the sun rises! Ride now! Ride, ride for
ruin and the worlds ending! Death! Death! Death!