Most D&D campaigns don't reach Tier 3 (that is to say levels 11+), which is a real shame when it comes to features and spells. At those levels, there is room for a lot of really, really funky stuff—stuff that doesn't necessarily break balance, but does break universal laws.
Now, I'm not a D&D lore guy, but one thing I know for sure (as it is used in the majority of fantasy settings, even beyond D&D) is that high level magic just isn't as common as low level magic. Even in magic rich settings such as Eberron, high magic is rare at best. The reason is simple: this is the magic that is simply beyond the scope of what many people should be able to do; if multiple parties could use this magic, the world would be changed heavily.
That is where the fun homebrew comes in!
At lower levels, most spells will focus around usability. Things like fireball, haste and shield are staples because they are good spells for what they do, and nothing can really stand up to those sorts of spells in the competition of limited spell lists. At higher levels, while this competition is still common, I've noticed that spells become less about the players, and more for the DMs to give to powerful rivals. Spells like disintegrate are good, great even, but what makes it a 6th-level spell isn't the damage (after all, all damage can be tweaked to fit the appropriate spell level), it's really the fact that things killed by this spell can only be brought back with the highest level of magic: wish and true resurrection. This shows us how serious spells can be at these levels, and that's where Circle of Time really draws its roots.
Recently, I read the novel Einstein's Dreams by Alan Lightman and it immediately had me thinking how magic in D&D could emulate the amazing worlds described. While most of the different models shown in the book were worldwide, stuff like time moving slower the higher you are, or the fastest you are going, a couple caught my eye as being perfect for a spell. Those criteria were simple, the effect described needed to not affect everything, but to still be impactful enough that if it were seen in the world, a player would be amazed. Circle of Time was based on a concept of a center of time somewhere in the world. The closer you were to the center, the slower time was for you, and the further you were, the faster time was (time is relative, after all). The novel talked about some people journeying to this center of time to endlessly receive good emotions such as pride, getting themselves frozen in time at the very center to forever enjoy the moment.
In the spell, these sorts of mechanics are reflected by paralysis at the center, and slower speeds as you grow closer. The spell is not really usable in combat, as it affects the entire area evenly, ally or foe, and is designed to trap you in it. Regardless, it's quite usable as a feature of a campaign. Perhaps a BBEG wishes to not grow old, trapping themselves in a Circle of Time to never lose their youth, or maybe a character is scared of something of their past, wishing to remove the problem through the passage of time by waiting in such a spell.
I hope this sort of spell is usable in your campaigns, whether by players or DMs. High level spells have always fascinated me, simply because of their astounding potential for world shattering effects, and I certainly plan on releasing others I've made!
P.S. I promise I'll be back to my regularly scheduled barbarians soon haha. I plan on having a couple other non-barbarian brews first, one post on the artificer class, one for some thematic magic items, and maybe one post on revising official content, but I think they'll all be pretty fun!
