This is a bit of tempo take on aggro Taunt Druid. You're still able to win to the face on turn 5 with an Arbor Up, but it has a much better mid-to-late game fueled by ability to somewhat easily get multiple Greybough's on the board. There are 3 solid paths to securing multiple Greyboughs:

1. Oracle of Elune combined with Razormane Battleguard
2. Mark of the Spikeshell on Greybough on the board
3. Moonlit Guidance for a Greybough or to draw into combos 1 or 2 above

Of course multiple Greyboughs isn't the entire point of the deck (although it is fun one), so don't be shy grabbing your 0 cost Frostsaber Matriarch with Moonlit Guidance, especially when you have an Oracle on the board.