Well, when I made this card, I thought "Mmm, this is just a Sundial that can prevent Fire Bolts and weapon (and allows you to attack) as well, and when it works, you still lose HP until it becomes 1. This card allows you to take more than 100 damage per turn, but that's a rare thing.". So I guess 5
and 4
is good cost for this.
But this card has some downsides, because, well, even a Shard of Gratitude can save your life even more if you know what you're doing.
If you want to pack 6 of these, chance is your hand will be filled with copies of this card.
Also, this can be stolen / destroyed. Not immaterial.