Sorry to my previous vote for
8: Forgetting, Because it could be nifty im sure there is some nice trick possible with it. (especialy If combined with 23:)
or if you run a deck with no tricks, and dont have any need to hold your cards, or an opponent that likes to play tricks.
I just liked Murky better
And now without further ado,
In no particular order these three should inmo form the winning list.
6: Brilliance
because its simple and elegant, and still has much potential.
23: Youth,
Think its more Balanced, if not just more fun, then Shard.
(And can actualy form combinations and tricks, instead of just boringly adding 5 at every point (see 8:) , And it inspires tactics and counter play like holding in your hands to prevent healing if you got no destroy instead of just beeing unable to influence stuff)
24: Murky,
Very original concept, Not to strong, still usefull, And very flavourfull really fits the concept of the Darkness Element.
Edit:
Tho honerable mention to
1: Preservance,
think its very nice, but Disquilify it from winning as i think its a bit to strong. (Vrt Said: winning card must not be Op.)
OverPowered = Unkillable and undeckable in 1 card, Yes please.
but thats my oppinion
and
7: Light,
Unlimited light producing Creatures for 6, But that 6 you'll get back asap +lots of intrest, Yes please (less Op. but still inmo
)