See these happy crabs? They're happy crabs, dancing around a tree with their starfish friend. You wouldn't hit the crabs, would you? Because they might hit back, and maybe the tree will, too.

A deck built around Assault Formation, with high-toughness creatures backing it up, though it started as a crab-focused deck. Sigiled Starfish is included to make finding it easier, because the deck just flat out can't win without Assault Formation. Hence why there's 4 of Assault Formation, because if one gets removed then it's bad news. Despite the name, there's only four crabs in the deck, mostly the one with the best use in the deck. Kraken Hatchling is a really good 1-drop for the deck. Ancient Crab would just be an all-round good heavy hitter once Assault Formation is out. Then...there's Tree of Redemption. Who'd have thought that with just a little enchantment, you could turn that useless card into an (effectively) 13/13 monster for 4 mana (6 if you include Assault Formation, 7 if you include using Assault Formation to remove defender).

Everything else in the deck are just tools to make it work better. Tower Defense is just a good tool for the deck, either being used to pump the creatures or better respond to flyers. Heroic Intervention is anti-wrath and all-round protection. Waxing Moon may seem like a strange inclusion, but it's the only card that gives just trample to all creatures I control at instant speed for 2 mana, at least as far as I could find. There's other cards with similar rates, but the instant speed is too much of a surprise win enabler to overlook. Nissa is support, which helps protect me and get through my deck to what I need.

The strategy is fairly straightforward. Block with my high-toughness creatures during the early game while I search for Assault Formation and Tree of Redemption, then play both and swing in with my now-suddenly-huge creatures, using Waxing Moon as a combat trick to trample over and Tower Defense to pump them if needed. Ideally, the play would be Kraken Hatchling on turn 1, Sigiled Starfish on turn 2, Ancient Crab on turn 3, Tree of Redemption on turn 4, then Assault Formation on turn 5 to enable Tree to attack and leave 2 mana open for Waxing Moon/Heroic Intervention.