The value of X is calculated only once, as Lydia Frye's last ability resolves
I believe it was made to work with Bound in Silence, which was a Rebel (the card introduced the tribal supertype)
The +1 is solid in a deck like Xenagos, God of Revels, which takes advantage of both the pump and the trample
And if you want to play with a house rule that the Graaz player get perks if they shout Im the juggernaut! when they enter combat, hey, go nuts
The flavor text adds so much to this card: you dont only have to fight these Fears within Duskmourn , but you also have to feel yourself being physically impacted by them
Also, imagine trying to attack an opponent with six mana up, a bunch of cards in hand, and three payoffs in playitd like be paralyzing, and your opponent could just keep making land drops while building up an even better defense you cant see