Ostimancy: 13 Extradimensional Spells For The Dangerously Curious

Ostimancy is magic that focuses on utilizing the power from alternate dimensions. Though some effects are pulled from more established planes of existence, most of them are from four Outer Planes called Ferrum, Lux, Speculo, and Tonitrus.


Home to the legendary artisan crafter known as Qalast, Ferrum was created as a Demiplane specifically to punish him. It is said Qalast angered a god long ago, by refusing to make them a weapon stronger than any other.

To punish Qalast, the god did two things: they cursed Qalast to have an insatiable urge to constantly create weapons, as none were ever good enough; they then created a Demiplane of which Qalast would spend eternity alone, with but a hammer, forge, anvil, and an infinite supply of iron to keep him company.


Little is known of Lux, as those who’ve managed to venture there never return. However, it is said to be a dimension composed entirely of radiant light.

Some think Lux to be much like that of the upper planes, while others see it as a terrible place of blinding light that should never be traversed.


Often called the Mirror Dimension, Speculo is said to hold every possible iteration of every living thing that has ever existed.

Though travel here has yet to be succeeded, some still think it possible.


A dimension composed of one terrible, unending storm, Tonitrus is said to be created by a Storm Giant that ascended to godhood.

The name of the fabled giant is unknown, but many have tried to weather the storm in search of them. The great storm is too treacherous a place for most adventurers, however, and most think such an endeavor a fool’s errand.


Though the above details on the Extradimensional Planes are included after the spells on page 6, I’ve included them here to give a better idea of what they are for interested folks. The information included about the planes is not at all intended to be a homebrew setting, as I know that’s not allowed on DMs Guild. If, for any reason, using the included alternate planes as the source of spells in considered a breach in the rules by the Guild, I will obviously take this down and rework the content to better reflect existing official content.


  • Hotfix (6/10/21) – Removed paladin from Flicker as paladin’s do not get cantrips. Replaced with cleric.

Thank You, Seriously

I put a lot of time into this stuff, mostly for my own players. That said, engaging with the incredible community on DMs Guild and the D&D community as a whole has been unlike any other experience. As always, any feedback on my work is much appreciated. It helps me, my players, and anyone else crazy enough to use the ridiculous things I have the privilege to make. Thank you for your support!


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