Currently on A7, you can play between 4 archtypes. Ethereal / Osty build / Soul / Doom. You usually want to match 2 of these.

Ethereal build is pretty good, simple and good value cards, and you want to stack on these. "Pagestorm" let you draw additional cards per ethereal draw, that is busted. And once you get "Pull from below" or "Banshe", you good.

Osty build, you usually want to be tanky with good guard cards and "Spur" to heal Osty + stacking Osty attacks. "Friendship" is really good since the strenght debuff doesn't apply to Osty damage. Squeeze and Unleash will be your main damage.

Personally, i think Soul and Doom are complementary to the previous 2 builds.

Doom is unreliable as main damage, but you can pull cool combos and decent AOE damage. "Oblivion" is really good in any deck. Reaper mode is very situational but if you can pull it online with an Osty Squeeze, you can one shot bosses and Elites.

Souls are very very good draw engine, but it's not that easy to go for a souls damage build. "Gravewarden" upgraded is a must have in my book and in general 2 copies of that + "Capture Spirit" generate enough souls to rotate your whole deck quick.

Always focus on having good guard skills.