Oh light, always getting of on endless crusades and holy stuff and whatnot....
Nevertheless, I believe the card is balanced. It feels like an inverse Phase Shield in a sense, and Momentum actually fits the card perfectly fine ("FOR THE HOLY GOD OF LIGHT, -WHATEVER HIS NAME WAS-!" is what I imagine Crusaders yelling while smacking down Permafrost Shields with Pulverizers and charging towards the opponent.)
At worst, if it REALLY needs a nerf, the cost could go up to 7 | 8 . I think it's fine though.