You think it’s worth pulling for it?
Short comparison is that Corvis Tome wins by +1 Atk/Def/Res+Guard, but U.Blooms have a 7 HP healing effect, which stacks even further with Mystic Boost.
And it can be refine, which can potentially add some more stats (i.e extra Def/Res).
…Those even stats look sexy as hell.
So it’s a matter of whether it’s worth giving up Guard, really.