haha great build mate love the way you made this, also I have no idea why but @0:23 I laughed a fair bit seeing your head pop through the cave entrance.
Terrain pieces to add to this set: 1) Minecart track that turns a sharp corner, going sideways along the turn. Can act as a curved barrier. 2) A wall of rock lined with a series of shelf mushrooms, with flat tops that can act as raised platforms. If this terrain set is missing anything, it's the ability to use the mushrooms themselves as elevation. 3) For that matter, a set of three regular mushrooms with flat tops, at varying heights, allowing them to be scaled. Almost like a "tower" of fungi. 4) Minecart track spanning two raised rocky outcroppings, acting as a bridge. Fighters can travel under the track as well.