The cards discussed can be viewed
here.
- Power cards are Dimensional Shield and Fractal. A deck with 6 Dimensional Shields can completely shut down a very sizable portion of the metagame, moreso than any other card. Fractal, which is often but not always paired with Dimensional Shield, provides immense late-game damage when paired with a good creature, typically Psion, Phase Recluse, or a low-cost attacker from another Element. Aether is weak to fast decks with permanent control (Deflagration, Steal, Pulverizer) or methods of bypassing shields (Shard of Freedom, Titan+Flying Weapon). Aether is strong against pretty much everything else, which is why it's arguably the game's strongest Element.
- An Element with a collection of solid cards, but no card that really sticks out the most. Air can run fast, pure damage decks with Shard of Freedom, although these typically only perform well with at least few upgrades for Damselfly and Elite Wyrm in particular. Air also has decent defensive cards, primarily Wings, Fog Shield, and Shockwave. Lastly, Flying Weapon works in a couple decks, which you'll see later. And if you somehow manage to come across 6 Blue Nymphs, that can be strong. Overall, Air is pretty solid on all fronts but lacks sheer power.
- Interesting Element because it doesn't have a very strong rush or stall, but it's still very strong overall. Key cards are Vampire Dagger, Devourer, Steal, and Nightmare. Vampire Dagger is arguably the strongest upgraded weapon because of it's sheer damage+healing, but it's weaker unupgraded. Devourer is a great denial card and is sometimes paired with Fractal for a total shutdown. Steal is probably the best permanent control card in the game, and Nightmare is useful in most situations and helps against Fractal decks.
- Key card here is Bone Wall, which is probably the second best shield in the game after Dimensional Shield, but it depends on the matchup. Bone Wall's use is blocking damage against decks with permanent control, or being paired with creature control such as Lightning. Note that Arsenic is useful for building up damage, and it's very strong in defensive decks with Bone Wall. Death is good against decks with low-health creatures through use of Bone Wall + Lightning/Shockwave/Fire Bolt. Death also has a pretty solid rush because it has efficient creatures.
- Probably a bottom-half Element, but it still has its uses. Basilisk Blood is the most reliable creature control card because it stops almost anything for 6 turns. Earthquake is useful for quanta denial but overrated in my opinion. Pulverizer has its uses against stalls or Dimensional Shield decks. Iridium Warden combos with Shard of Patience.
- Power card is Discord, which is arguably the best unupgraded weapon. Discord + 6 Purple Dragons can tear through slower decks, unless they have a good Shield. Nova is also good in rainbow decks - you'll encounter those soon enough. Ironically rainbows are probably the best answer to Discord.
- Now this is an Element! Power cards are Phoenix, Fire Bolt, Fahrenheit, Deflagration, Immolation, Lava Golem. Yes, these are a lot of power cards! Phoenix is a great attacker, efficient and hard to kill. Fire Bolt is a great control card that works against creatures or the opponent directly. Fahrenheit is a very strong weapon in stalls. Deflagration is useful as one of the few permanent control cards. Immolation and Lava Golem typically go hand-in-hand, along with some sort of fodder such as Photon, to produce extremely fast rushes. Fire can also be combined with healing cards (Sanctuary, Shard of Gratitude) to make very good stalls. You'll notice that Fire Bolt and Fahrenheit are great in stall decks because they accumulate high amounts of quanta.
- One of the weaker Elements, especially in a low-upgrades environment, but it does have one good deck. Its best deck is Titan + Flying Weapon, which completely tears through stall decks, especially with Catapult added in.
- There's a running joke that there are only 11 Elements, because Life is so weak. Let's move on.
- Good stall Element because of Sanctuary and Miracle. That's about it, though. Light typically has to be combined with another Element, such as Fire, which provides creature control.
- Not much to see here. Sundial is useful in stalls. Reverse Time is good against Nova and Immolation decks. Somehow Spike managed to get 3rd in War with this Element, but that was more due to Spike than the Time Element itself.
- Power cards are Shard of Patience and Nymph's Tears, or even better if you have Nymph Queens. Both of these cards can build up massive amounts of damage. Water's defenses are a little shaky though, and it can't rush too well either.
Overall, I'd place Aether/Fire/Darkness at the top, followed by Entropy/Air/Death, and then the rest.