Updated: No new draw mechanisms from RoS that help this deck, but there's some pretty high value cards that do a serviceable job and most of this deck is in the buffs anyway.  I'm not holding my breath for this to be huge, but given how well the deck has worked for me in the past and the number of cards that didn't rotate, I intend to try this deck early.  I also intend to keep this deck a budget version so the only Legendary included is Zilliax.

Old version: https://www.hearthpwn.com/decks/1185992-mech-druid-rank-5-budget

    The idea is pretty simple: make boards that are tough/expensive for your opponent to clear and do so repeatedly until stuff sticks.  Buff said stuff=>win.  It should be noted here that this is NOT like the Wispering Woods + Soul of the Forest OTK-ish deck with 20 control cards.  This is a more mid-rangey deck that wants to get a few chunks of damage over multiple turns before going for the kill.  If you super high roll, or your opponent gets very few early game cards, you can/will win on turn 5 or 6, but most of your wins are more mid-game timed and going too hard too early can blow your hand too soon and leave you at the mercy of top-decking.

   Cards like Mecharoo, Safeguard, and Replicating Menace are good for preempting board clears to help ensure you have something to buff the next turn, but you don't need to wait for these to play out onto the board. Savage Roar is obviously a finisher, but if you get a good opportunity to use it for less-than-lethal-but-still-a-buttload of damage, you should do it. There are a ton of buffs in this deck and it can sometimes be a challenge to make use of every one you draw so you can and should use them more freely than you would in other decks.

Use your magnetic cards to beef up your chip damage or make advantageous trades.

   I have experimented with Scarab Egg and it doesn't suck.  With lots of buff cards it is usually more than just an 0/2 that your opponent leaves up the whole game.  It hasn't made the cut for me in the past but I don't hate it and it is good against board-clear heavy decks.