You may reveal an artifact or enchantment card from among them and put it into your hand
And the reward on the backside is basically Moan of the Unhallowed with the ability to really slowly hate on the graveyard and make more 2/2s
Like most Magic: The Gathering cards, the value of All That Glitters depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Fallout)
Then your creature spells cost 1 mana less to cast for each +1/+1 counter it has
And then you can tap and shoot something for a damage as well, and layer damage onto creatures from other source, be a threat to small fry, and otherwise be involved with playing Magic
Hurkyl need not have been on the battlefield at the time the noncreature spells were cast for the ability to trigger or for the spells to be counted