Ok I have a suggestion for a higher tier boss. I call it the Planetcracker/Omega-Drill. The basic idea of this boss is that it is a giant sized drill that when spawned, begins drilling down towards the planet core(lava). Basically, the player must destroy the boss BEFORE it reaches the lava or the item drop is lost. This boss features 2 gun turrets on its main body and possesses high armor defense. Touching the drill will result in high damage dealt to the player. I've drawn up a quick sketch of what it should look like: As for the spawning item I was thinking perhaps something like a Rare Gem Showcase, where the story is that greedy mining guilds think that this showcase is displaying some sort of rare gem, and that it must be hidden somewhere down in the planet you're currently on. So they decided to send one of its mighty Planetcracker drilling machines to scour the planet for this gem.