Makishima
Golem
I'm not talking about the tooltip by the way ; the Rainbow Crystal Staff might be a reference to Lovecraftian Cthulhu mythos, more specifically in "The Haunter of the Dark", one of the protagonists discovers an artifact called the Shining Trapezohedron, and it is capable of summoning terrible things from the depths of space and time. And if you look at the crystal summoned by the Rainbow Crystal Staff it does indeed seem to be a trapezohedron, and it's already pretty shining. This is reinforced by the fact that it is a drop from the Moon Lord, which is essentially a Lovecraftian cosmic god very possibly related to Cthulhu.