Spellbook of the Celestial Spheres

Subtitled: A Treatise on the Creation and Detonation of Multi-Dimensional Temporal Spheres. This thin, leather volume is a spell book in an ancient elven magical tradition that is a predecessor of the modern school of evocation. It was found in a warded circle next to the dead body of Galathi in the ruined city of Kithkaira.

Appearance

The book is a thin, leather volume of approximately fifty pages. The first half of the book is entirely dedicated to extremely advanced math and geometry that is beyond the understanding of the people of The Riding. The second half of the book is devoted to a series of spells that progress in complexity, each building on the other, until culminating in the final spell in the book. All notations are written in elven.

Spells 

Rhythm of the Celestial Spheres

This spell is similar to Leomund's Tiny Hut, only in a much older tradition. It is evident that the modern version of the spell is a direct descendent of this one.

3rd-level evocation

A 10-foot-radius dome appears around you and up to nine Medium or smaller creatures in the area. The spell fails if there is a creature larger than Medium or more than nine creatures. The spell ends if you leave its area.

The dome is immobile. Until the spell ends, you can make the inside be dimly lit or dark. The outside is opaque of any color you choose, but is transparent on the inside.

Creatures and objects in the dome's area when you cast the spell can move through it freely. Everything else is unable to enter. Spells and other magical effects can't pass the barrier of the dome on either end. The dome's atmosphere is always comfortable and dry, no matter the outside weather.

Harmony of the Celestial Spheres

This spell appears to be the magical predecessor to Wall of Force, Wall of Fire and other similar spells.

5th-level evocation

A hollow, nearly transparent, curved surface appears at a point you choose. It can be in any orientation. You can form it into a dome or sphere with a 10ft radius. The wall of the sphere is always 1/4 inch thick. If the wall is in a creature's space when it appears, the creature is pushed to a side of the wall that you choose. The spell must be keyed to one of the four elemental planes and draws its power from that. The caster is required to possess an appropriate, magical conduit to the selected plane.

The sphere may be freely passed through by a person or item of sufficient power that is keyed to the corresponding elemental plane. Typical items would include holy symbols to gods associated with that elemental plane or magic items formed of its essence.  Otherwise it is immune to all damage and can't be dispelled by Dispel Magic. Disintegrate destroys the wall instantly, however. The wall also extends into the Ethereal Plane.

The exact composition and behavior of the sphere wall depends on the associated elemental plane:

• Fire - The surface is tacky, yields to the touch as if it is elastic, and will adhere to items that attempt to pass through it. An attempt by a creature to reach through may result in them being trapped in the sphere wall material. Trapped creatures require a strength ability check to extricate themselves. The DC should start at 15, but could increase as high as 25 depending on the interaction between the creature and the sphere.
• Earth - The surface is cool and smooth and will yield a few inches to gentle pressure. Light pressing on the surface will create ripples that move across the surface of the sphere. Attempts to strike it will result in the surface appearing to be as unyielding as stone. 
• Air - The surface is warm and viscous. Creatures can draw lines and shapes in the surface of the sphere to a depth of one inch that will remain for twenty four hours before disappearing.
• Water - The surface is as smooth as glass and as unyielding as stone. No action by a creature will make any mark or have any effect of the surface.

Casting the spell at a higher level allows for the radius of the sphere to increase by 5 feet for each spell level above 5th.

Melody of the Celestial Spheres

This spell appears to be the magical predecessor to Forcecage and other similar spells.

7th-level evocation
Casting Time 4 hours (Ritual)

An immobile, nearly transparent, sphere of elemental force with a radius of 20 feet springs into existence around an area you choose within range.

When you cast the spell, any creature that is completely inside the surface area is trapped. Creatures only partially within the area, or those too large to fit inside the area, are pushed away from the center of the area until they are completely outside the area. The spell must be keyed to one of the four elemental planes and draws its power from that. The caster is required to possess an appropriate, magical conduit to the selected plane.

A creature cannot pass through the created wall by nonmagical means. If the creature tries to use teleportation or interplanar travel to leave the cage, it must first make a Charisma saving throw. On a success, the creature can use that magic to exit the cage. On a failure, the creature can’t exit the cage, wastes the use of the spell or effect, and will never succeed on any future attempt. The cage also extends into the Ethereal Plane, blocking ethereal travel. This spell can’t be dispelled by dispel magic.

The behavior of the sphere varies based on the elemental force used to power the spell.

• Fire
  • The surface is tacky, yields to the touch as if it is elastic, and will attempt to draw items or creatures that touch it into its interior. An attempt by a creature to reach through may result in them being drawn into and trapped within the sphere. Creatures being pulled into the sphere require a strength ability check to extricate themselves. The DC should start at 15, but could increase as high as 25 depending on the interaction between the creature and the sphere. On a failed throw, the creature is pulled within and subject to the effects of the sphere's interior.
  • Creatures tracked entirely within the sphere will appear stuck within the viscous contents of the sphere. Items and creatures may appear suspended within the sphere. For creatures trapped within, time does not appear to move and they require no air or sustenance, but are also unaware and are unable to move.
• Earth
  • The surface is cool and smooth and will yield a few inches to gentle pressure. Light pressing on the surface will create ripples that move across the surface of the sphere. Attempts to strike it will result in the surface appearing to be as unyielding as stone. 
  • While within the sphere, time passes for creatures and they are forced to eat and sleep to maintain themselves. Other natural processes within the sphere are suspended as only conscious creatures will be able to function. Looking out of the sphere from within, it will appear as if the world is frozen in time. Upon emerging from this type of sphere, it will appear to creatures that were within that no time at all had passed in the outside world. 
• Air
  • The surface is warm and viscous. Creatures can draw lines and shapes in the surface of the sphere to a depth of one inch that will remain for twenty four hours before disappearing.
  • Creatures within the sphere float suspended within the elemental contents of the sphere, cannot move and not affected by the passage of time. However, their minds are active and they are aware of everything occurring outside of the sphere.
• Water
  • The surface is as smooth as glass and as unyielding as stone. No action by a creature will make any mark or have any effect of the surface.
  • Creatures trapped within the sphere will feel the passage of time and will be able to move within the sphere, but all other temporal effects are suspended. There is no need for food or air or sleep. Items do not decay. Time passes within the sphere at the same rate it does outside the sphere.

Orchestra of the Celestial Spheres

This spell appears to be a carefully planned, simultaneous casting of all four types of spheres available in Melody of the Celestial Spheres.

9th-level evocation
Casting Time 4 hours (Ritual)

A caster of this spell can tear open a gateway in the fabric of reality and potentially allow themselves and up to 8 willing or unwilling creatures within the ten-foot diameter arcane circle drawn during the ritual casting of this spell to appear anywhere and at any time in the Prime Material Plane, its mirror planes, the Ethereal Plane, and each Elemental Plane. The caster's ability to place the other end of the gateway in the desired physical and temporal location is bound only by their ability to perform the correct multi-dimensional, geometric calculations.

Any caster of this spell must make an intelligence check against DC 25. Failure results in the fraying of the very reality of the caster and their eventual death in 4d6 hours. Casters dying in this fashion cannot be bought back to life by any spell except Wish. The tears in the multi-planar fabric created by both gates never truly heal and remain targets for others wishing to travel or influence events across multiple planes.

Cacophony of the Celestial Spheres

This spell appears to be a carefully planned, intentional miscasting of Orchestra of the Celestial Spheres

9th-level evocation
Casting Time 1 day (Ritual)

The caster draws an arcane ring and the appropriate sigils to invoke elemental energies from all four elemental planes in the same fashion as Orchestra of the Celestial Spheres. Only, in this case, the caster deliberately causes undesirable resonances between the various elements. This ultimately results in a catastrophic explosion of elemental forces causing 12d12 points each of fire, bludgeoning, thunder, cold and psychic damage. This damage is sustained by all creatures and structures within a 400 foot radius. In addition, the aftermath of this spell will result in 2d6 spheres - equivalent to those summoned by Melody of the Celestial Spheres and of random elemental composition - appearing within the affected radius. 

Before being affected by the damage caused by the spell, any caster must make an Intelligence check against DC 25 or immediately die from the strain of casting the spell. Casters dying in this fashion cannot be bought back to life by any spell except Wish. 

The damage to the inter-planal attributes of the effected area will be visible in the Prime Material Plane, its mirror planes, the Ethereal Plane, and each Elemental Plane. This damage and the spheres created in its aftermath cannot be fully dispelled until the arcane ring drawn in the casting of the spell is destroyed. Even afterwards, imperfections in the structure of the underlying physical planes make the effected area particularly susceptible to trans-planar activities.