Resurgence Gemshell 7s
I'm a big fan of Gemshell decks. Depending on the meta, different styles of Gemshell decks will work better. A mostly blue Gemshell deck, focusing on cards that benefit from 7+ faeria cost cards is one of my favorite variants, but it's got two weaknesses: yellow rush and red burn (a red focused Gemshell deck can work well in metas where those are dominant). This deck is particularly strong against decks that rely on a few super strong creatures, like Soul Eater, as it's got transforms through mirror phantasm and some other useful control tools. The current meta is very diverse, and this deck got me to god rank on a long win-streak, earning #7 (Which I'm sure will not hold). I've seen a few good players like Superblizard playing similar decks, but I don't think it's popular yet. The deck can work defensively, and usually is greedier than other decks, but it can also be played aggressively with the right start. Good openers are Gabrian Commander, Water Elemental, Spring Mochi and Gabrian Archon in that order. For lands, you can make do with 4 lakes, 2 mountains or 3 lakes 3 mountains. Lakes are generally more useful, but the mountains should be placed somewhere that they can be useful for rakoakopter/garudan if possible (though you may want to save well spots for archons). Lands can be played defensively or in lines for archons to move, depending on your opener and the matchup.
I ranked it as expert because it's a control deck and to play well you need to: be in the right meta/adjust to fit the meta, be able to predict your opponent's likely moves, know when to play defensively and when to go all in on offense (it's often the greedier deck, so board control is usually the right play, but not always), spend faeria at the right times (often saving faeria for a big swing turn is the right move) and know when hellfire is a safe or risky play.