I hid some kind of glitch this morning (12:53 AM EST). I was playing in an Arena game, as a Mage. I cast Arcane Intellect, drew my 2 cards. Can't remember the first one, but the second one was a Fireball.

At first, the Fireball didn't show up in my hand. I moused back and forth, over the cards, and it suddenly appeared. Then, I clicked to cast it, chose my opponent, and the spell took the mana out to cast, but didn't actually cast. When I clicked on it again, it told me that I didn't have enough mana to cast it.