What i think about Lunar boss is UFO. a huge UFO that is spawning aliens with S.D.M.G's. an alien has 5% to drop an S.D.M.G.
Space parts: (the UFO will drop one of those)
Rocket Engine (25%)
Space Glass (25%)
Gravity Machine (25%)
Space Turbo (25%)
Can drop also:
70% Ray Gun
Golden Cog (Summons a robot pet that will fight for you) 15%
40-70 souls of flight 100%
30-40 Space Ingots.
With Rocket Engine, Space Glass, Gravity Machine, Space Turbo, 40 Space Ingots and 50 souls of flight you can make a small space ship. With this space ship you can travel to Moon, Venus, Mars, Jupiter and Neptune.
10 Space Ingots + 20 souls of flight = Robot Wings
HOW TO SUMMON
To summon UFO you will need Mechanical skull, Mechanical Eye, Shadow Orb and 10 Adamanite OR 10 Tianium bars to get Radioator.
Click on radioator and it will say
Something has landed to Planet...
and there we go.