Hearthpwn

Btw the dream combo is playing nzoth, ironbark on nzoth then innervate or lightning bloom to play mark of the spikeshell on nzoth. To potentially play nzoth again and give plaguemaw huge value (since it's also summoned by nzoth). Good luck!

accidentally posted in between typing, hopes this helps :)

2 lunar eclipse

2 mark of the spikeshell

1 archspore mashifin

2 dreaming drake

2 wild growth

2 circus amalgan

2 overgrowth

1 plaguemaw the rotting

1 burning blade acolyte

1 greybough

2 druid of the plains

1 cenarion ward

1 nzoth god of the deep

1 scrapyard collosus

I'm currently after the same achievement as you, and in the same boat as you are skill-wise. This is the deck I'm seeing decent success with (at diamond 4 atm) and making progress towards the achievement:

1 Innervate

2 lightning bloom

2 nature studies

2 guess the weight

2 ironbark