Its almost strictly better Tuinvale Treefolk mixed with Greater Sandwurm. I think that if you support counters matter theme in your cube, as I do in mine, it is playable as an instant, albeit expensive way to put counters on something like Sharktocrab, thats still a creature. Also apparently it's the first time we got "can't be blocked by creatures with power 3 or less" on a creature that doesn't have 1 or 2 toughness.
My Gruul archetype is high power matters. Of all the RG commons and uncommons that could serve as signposts for the color pair I found power matters the only one that is represented on enough cubable red cards. And in my cube high power overlaps with equipment theme in RW and counters in GW and GB. RG spells lacks green cards, RG counters red cards, RG landfall lacks good cards, as do werewolves. Ramp, as was mentioned before, lacks red payoffs. There are enough red and green elementals to try to make it tribal archetype, but those cards seem weak and unappealing.
Considering ruling on the new doublefaced cards, allowing casting the higher CMC side of those cards, we could at least consider some of those cards as a transformational sideboard options. I used to run kor firewalker for burn matchup in the side. Potential sub 3 CMC spells:
Aldrund, God of Cosmos - I see no use for eithe side
Cosima, God of Voyage - same
Halvar, God of Battle - i think the rules allow to cast him, even if its the backside has the lower CMC, not front side, but again, no use for it even in the UW living end variant
Kolvori, God of Kinship - either side is useless
Tolvar, God of Fury - creature side would be a winmore card, if you already have battlefield presence, artifact side useless
Egon, God of Death - Throne of Death side fills up the graveyard, but its not somethnig deckwarping
Valki, God of Lies - the only one that shows some promise i think. I could see using the Tibalt side alongside living end against control, just to overload opponents counterspells and with hope of exiling their graveyard hate and counterspells. We could in theory have 7 mana planeswalker on turn 2 with Simian Spirit Guide, and its a way to win with empty graveyard
Aldrund, God of Cosmos - I see no use for eithe side
Cosima, God of Voyage - same
Halvar, God of Battle - i think the rules allow to cast him, even if its the backside has the lower CMC, not front side, but again, no use for it even in the UW living end variant
Kolvori, God of Kinship - either side is useless
Tolvar, God of Fury - creature side would be a winmore card, if you already have battlefield presence, artifact side useless
Egon, God of Death - Throne of Death side fills up the graveyard, but its not somethnig deckwarping
Valki, God of Lies - the only one that shows some promise i think. I could see using the Tibalt side alongside living end against control, just to overload opponents counterspells and with hope of exiling their graveyard hate and counterspells. We could in theory have 7 mana planeswalker on turn 2 with Simian Spirit Guide, and its a way to win with empty graveyard