As we seem to have a fairly complete strategy list on typewithme, I decided to put it here to unclutter. Also, this way we can comment/adjust as vaults change. I'd imagine the goal should be to reach a consensus for versing each element with a bolded deck for round 1.
EntropyStrong Cards to Counter: Pandemonium, Discord, Nova, Butterfly Effect, AM
Expected Decks: Anything with discord, Scrambled shriekers, Mono Entropy and Darkness Duo
Strategy?: Protect against scramble w/ Sanct, BE w/ PA, Pande w/ high hp creatures Antimatter makes dragons/Saders problematic
Possible decks to counter with:Max HP (with sanc and PA for the pillars), Immo Rush, Flying Glories, Desert Crusaders to a lesser degree,
Anticord DeathStrong Cards to Counter: Bonewall, Poison Cards, Plague
Expected Decks: mummy rush, speed poison Bonewalls and CC to fuel them
Strategy?: Protect against plague w/ archangels, Poison w/ purify, Bonewall spam creatures/momentum
Possible decks to counter with: Firestall (with deflag), Waterstall (with purify)
GravityStrong Cards to Counter: Otyughs, Momentum, Pulverizer (not that much in last war), Acceleration, Charger, BH
Expected Decks: Discord BH, Acceleration Voodoos, Random duos with charger and otyugh
Strategy?: Plan to rush as gravity plays slow and then picks up speed? Protect perms with PA? Play PotS. Once you've scouted enough, counterdeck.
Possible decks to counter with: PotS (I haven't found anything else that beats Discord BH, Otyughs, Momentum, and Acceleration)
EarthStrong Cards to Counter: EQ, BB, Wardens, Graboids, Stone Skin
Expected Decks: Stalls, Scrambled Shriekers, Darkness denial, RT graboids, Immo, Voodoo
Strategy?: Rush hard. 42 card deckout.
Possible decks to counter with: Graboid Pegasus Rushbow (I think earth will play denials against us), 42 card deckout (their largest decks are 40 cards)
LifeStrong Cards to Counter: Mitosis, Adrenaline, Healing
Expected Decks: Adrenaline (staves, graboidbow), FFQ, 40-card semi-stalls, Fractal frogs, adrenavamps
Strategy?: Stall for deckout and lobotomize? Skull shield and fire shield are good for pseudo mass CC. Graboids too, to take advantage of life's lack of instant CC.
Possible decks to counter with: Poison Sanc Stall, Firestall, Pegasus Graboid Rushbow, Peggy/Wings, Blessed otyughs/miracle
FireStrong Cards to Counter: Immolation, Phoenix, Fahrenheit, Bolt, Lava Golems, Buckler
Expected Decks:fire stall, immo rush, graboid rainbow
Strategy?: Fire is tricky because they can use both rush and stall. Scouting is key.
Possible decks to counter with: Graboid Pegasus Rushbow, Desert Crusaders, Oty Lock w/ momentum?, Firestall with 2 reflective shields
WaterStrong Cards to Counter: Toadfish, Steam Machine, Chrysaora, Arctic Squid, Ice Shield/Freezing Cards, Inundation (when paired with antimatter)
Expected Decks: steam machine/phoenix/explosion, Squid + Toad + Owl's, Poison Rush, Waterstall with bolts
Strategy?: Water's strength is in CC. They have squids, toadfish, and can use owl's eyes. Additionally, they have steam machines to break through
stalls.
Possible decks to counter with: Fire stall, Water duo from War 2? dune scorp/rewind, Peggy/Wings, Discorders
AirStrong Cards to Counter: Shields (Wings/Fog/Hope), OE, FFQ, Flying Weapon
Expected Decks: This one's a bit tricky, as air can indirectly duo with many elements. Note that most of their decks have decent amounts of CC, healing, or shielding. Flying titans?
Strategy?: Prediction will be key as countering rush with CC & stopping FFQ stall will vary greatly in counter strategy
Possible decks to counter with: Deckout, poison stall, winged creatures.
TimeStrong Cards to Counter: Rewind, Eternity, GoTP/Nightmare, Dune Scorpions
Expected Decks:dune scorps, graboids, GotP nightmare, random duos that use RT and dragons
Strategy?: Sanctuary stall. It beats nigthmare and the CC they often use. Don't use deckout unless you have a lot of PC for the eternitus (plural of eternity).
Possible decks to counter with: Poison Sanc Stall, Firestall
DarknessStrong Cards to Counter: Steal, Vamp Cards, Devourers
Expected Decks: Devourers, Graboid Rainbow, Steals in almost every deck (especially against light)
Strategy?: Rush with PC, Wardens
Possible decks to counter with: Graboid Pegasus Rush, Immo Rush, Blessed Wardens (hrmmms modification)
AetherStrong Cards to Counter: Phase Shield, PU, Lobotomizer, Mindgate, Fractal
Expected Decks: Fractal devourers or frogs, dimensional shield stall, PU anything, mindgate stall
Strategy?: I would fully expect mindgate if they expect any sort of stall Denial and PC. Deckout stall. Rush with PC.
Possible decks to counter with: Discorders, Immo Rush, Max HP (beware of mindgate...although nothing to power earth with...still could lead to deckout for us not if we have more cards. 36 cards is good. Aether never had anything >35 last war)They will have a different deckbuilder this war.
UnderworldStrong Cards to Counter: All cards from the above elements. Underworld doesn't have the elemental limitation any of us do, so until we see their decks in action we can't really tell.
Expected Decks: Possbily rainbows?
Strategy?: Don't use discord. Also, UW reveals there whole vault after they play just one round (which is round 5). So we can then see all of the cards they have left except for salvages. We'll have an easier time countering them after Round 5; just keep our vault adaptable.
Possible decks to counter with: Blessed Otyughs with 2 BHs. Poison of the Sun (RT > Nova and SNova)
Bolded decks indicate those with a high expected winning percentage.
"Chance favors the prepared mind" - Louis Pasteur