I wondered at first if 7 gems (6 net gain) is too much. I considered its use in three situations.
In a Holy deck, you would only need to add this card for excellent synergy since you can play it any time you draw a second one, eliminating both. There's no need to toss in any additional Undead cards to benefit from it, and in the mean time, it's another Holy keyword in hand (for that oh-so useful Holy effect). Then again, you do still have the ashes to contend with, even if you're likely getting the gem for playing it.
It would certainly be fun to play with in an Undead deck, not knowing what you're going to discard. Gems are certainly useful.
You could justifiably add it as well to decks that are neither Holy nor Undead and play it when two are in hand, though then the keywords don't do you any good. Unless you're playing against a Holy deck, in which case being Holy gives you occasional stock and being Undead makes you an occasional target.
All this considered, I figure a net gain of 6 gems isn't too much after all, ashes taken into consideration.