27.06 update:

Deck optimized for thresholds, you Mulligan for fixing first to 1 earth 1 water 1 air. With correct mulligans the success rate is 90% to be on curve with thresholds (see 6-7 sites) by 8 sites seen the odds of fixing the curve is more then 95%, that is the power of Elementalist. If you want to see 1 water and 1 air and 1 earth by 5 sites seen the success rate is 85%.

Keep immediately:

Earth×2 + anything
Earth+Water + Earth+Air
Earth + Air+Water
Earth + Water + Air

Corrected the early game and mana ramp with Kettletops and Humble Villages, taking away little from late game, but massively fixing early game pressure and Agro matchups as well as Geomancer.

DECK:

Deck tries to pressure to lead the game. Deck performs well and is balanced. Its Earth and Water deck (beefy minions), that can use mass removal from fire and air and mobility of air and water. Into Agro you want Sister Stephania or Pebbled Paths to comfortably make it to midrange. Into midrange you compete with value. Against control (Archimago) you play hate sites and play agressively.

GAMEPLAN:

You play the best value cards in earth and water with best support in air and try to play agressively and close the game by late midgame. Play back row into Agro and be mindfull of minion placement (Bane of Aventis). You play a control value game, winning in late midrange by getting more value out of your cards then opponents.YOU MUST ANY CHANCE YOU GET TAP TO DRAW SITES AND NOT SKIP DRAWING SPELL FOR TURN. For this you will want to see a city or tower in starting hand, to make it easier by getting to 4 mana in 3 sites. At most you want to draw 1 site for turn so you don't lag behind when appropriate in early game.

PLAY:

You want to swarm the board fast and be agressive before you get to top deck mode (lugbog, unicorns, orders,... turn 2 and forward using towers and cities for mana ramp whenever possible). You play best value per mana cards so top deck mode is okay, and curve is adjusted for topdeck mode if the game happens to go long. So when possible tap to draw sites and prolong the hand size. Only draw 1 site if you happen to have a 3 cards in hand 4 mana and up.

You play hate sites to lock archimago as that is the worst matchup and garden of eden to counter deck draw builds, playing into magoo or sorcerer you want to mill your sites until you get hate sites.

SITES:

You need 2 air threshold so mulligan when you have multiple starting hand as you only need one. Prioritise getting 3 earth threshold before 3 water, and adjust this to cards drawn, you need 3 earth threshold faster then water.

PLACEMENT:

Into agro you play back row and defensively and you should win.

Into other midrange you outvalue them if you play smart.

Into control you go extra agressive while keeping mass removal cards in mind (play around whirling blades, poison novas, atlantean fate, earthquake)..

SWITCHES:

CAN CUT:

1s: 1 Plague of Frogs (defensive card, you try to be agro, but is a good fallback card and can defend while you go agro in enemy territory)

2s: 1 Pied Piper (meta call)

3s: 2 Fey Changeling (meta call) Can swap Orders (Oak)

4s: 1 Queen Guinevere 1 Captaing Baldessare (good combo and removal bait)

5s: 1 Lilith (removal bait)m Book of the Dead

6s: 1 Rhitta Gawr of Snowdonia (stabilising, must remove and hard to remove threat)

City of traitors (ramps you and if you play agro opponent will have to deal with your minions, card is very bad into Agro, but good into all else) for Danybrook Inn or colour out of space.

CAN INCLUDE:

3 Phase Assassin (They will add to the agressive tempo but are bad defensively, so good into anything but agro, same as Fey Changeling so these two can be swaped, but threshold wise they can brick as you play as little air sites as possible).

2 Atlas Wanderers (Can open up an opponents site for swings, great into control lists not so good into agro, adjust acordingly. Can swap out Lilith and Rhitta Gawr of Snowdonia)

Any two really good 4 drops could replace Captain Baldessare and Queen Guinevere, but if find them working in line with the deck, Captain Baldessare can net you card advantage into late game and is a must remove threat, which frees up other minions to attack, and Queen Guinevere is double swing with Unicorns and Cats and Tempo gain, also must remove threat, so it leaves your other minions to attack.

2 Abaddon Succubus for agro, but not realy necessary.

1 Highland Princess and 1 Torshammer trinket (take out 1 Swap and 1 Book of the Dead) - have more finishing power and play with ring of Morrigan more, but have worse late game draws.

Dried Mud (E+WA)

@treexnerd