Unlike the shard of protection, this one doesn't feel... epic. ^^;
The only cards that I can think of that would greatly benefit from having multiples of these cards on the field are Antimatter, Fractal, Miracle, Nymph's Tears, and Rain of Fire. Many spell cards (upgraded) already have super cheap costs of 3 or less, so perhaps one of these can help out, but playing any more than 2 or 3 wouldn't benefit a deck that's utilizing a lot of spells (Deflagration costs 1, Improved Steal only costs 3, etc.).
This does however make the other spell shards cheaper (which is nice), and also assists with Nymph-decks and Fractal decks, simply because of the minimum requirement to play those spell cards.