In Franz Bardon's Practice of Magical Evocation, Bardon reveals that Aschmunadai is a spirit with the rank of absolute monarch that is leading the beings of the Earth Zone.
As is the case with a lot of the hermetic spirits, not much information can be found on him on the internet or in books. I would like to remedy this as best as I can, though I must be brief.
The statements on the net made by others that I remember best are that Aschmunadai was the "boss of Bardon's grimoire", and that he was the same spirit as Asmodai, or Asmodeus. After my evocation I feel that the first statement is not really fitting, and the latter is simply not true. It is clear to me that whoever made these statements has never been in their current incarnation in conscious contact with Aschmunadai, and that they are just making assumptions after having read what Bardon wrote.
I have obtained everything that follows by being in direct contact with Aschmunadai.
Aschmunadai has a tendency towards male energy, but overall he's pretty balanced. In fact the works of equilibrium everywhere are one of his specialties. He is also an expert on the ongoing act of creation that is performed by all that is in existence, and helps the magician with insights on how to become a more conscious creator, and how to use astra-mental laws to better effect. I cannot reveal more here on these subjects, except that this is a time when more and more of this information is becoming accessible through the various ways of the Earth Zone spirits.
Apart from these domains his primary office is the coordination of all the works of the spirits of the Earth Zone, and their interaction with higher planetary realms and the physical dimension, assuring that all is enacted according to the laws of the planes involved for best effect. All heads of the Earth Zone report to him or his deputies, and discuss their long term plans and actions with him.
Aschmunadai is wisely compassionate, although be might appear a bit blunt and aloof on the surface. He is a very busy spirit indeed, so do not tarry when communicating with him. Show him the respect that he commands.
He is extremely mighty, knowledgeable and powerful, and has an intense aura of mystery about him. Every serious hermetic magician should at some point seek to contact him.
High praise be to Aschmunadai, Philosopher-Mage-King of the Earth Zone.