To me, it was never about the gravity shield. I think that the #1 most overlooked thing in this game is the value of variety. Each different card in your hand represents a different choice you could make. You're rather limited when you only have dragons, shields, and pillars in your deck. Simplicity is not the way to go, unless you want a game that requires little or no thought. Say you had 21 Aether quanta...you could play both a dragon and an immortal. Or say that your opponent only has 1-5 health points left (after you would damage them, if you have dragons out) and you're really low on quanta...although I realize that this particular situation is pretty rare, it still presents another possibility entirely. Or maybe you're in a situation where they have a Gravity Shield and you don't have or can't play a Steal...there are really virtually infinite situations in which an Immortal would be preferable to a Dragon. Plus, the damage to cost ratio is exactly the same. Of course, the dragon is worth more because it's a single card. Two Immortals equals a Dragon in combined attack and cost, but you'd have one less card to play...and like I said before, having more cards is very important (specifically a wider variety). So there are drawbacks, but the benefits outweigh the costs. It's for that reason that I would highly recommend at least one Immortal, up to two.