The Father

First strike, vigilance
When the Father or another knight enters the battlefield under your control, you may choose to slay a dragon.
When the Father enters the battlefield, if a dragon was slayed, and the dragon died when being slayed, and if you don't control a creature named the Big Bad Blue Dragon create the Big Bad Blue Dragon, a legendary 6/6 blue and black Dragon creature token with flying.
Whenever a knight you control slays a dragon, and the dragon dies, you gain life equal to that dragons tou