Striker, Corwin's Companion

If you control Corwin, Champion of Magicka,
you may cast Striker from your hand
without paying its mana cost.
Dragon's Breath
{1}{r}{r} Tap Corwin,
Striker gets two counters with
"{t}remove a counter, Striker deals 3 damage
to target attacking or blocking creature,
this damage ignores any protection from green sources"