Those of you who have VR headsets would know about the mod Vivecraft, even those of you without knowledge of this excellent mod would be aware of it from various youtubers and such (Especially because being a youtuber seems to mean you just get handed a free Oculus Rift S if you so much as mention VR one time).
For those who don't know, Vivecraft is a mod which makes the Java version of minecraft playable in roomscale Virtual Reality. for the HTC Vive and Oculus Rift headsets, seeing how far we have come in modding has been incredible to say the least if a mod like this even exists.
The downside of course to playing with Vivecraft is that there are a few mods which do not work well in Virtual Reality, and while the creator of Vivecraft is working hard to make a few of these well known magic mods compatible with Vivecraft, I would like to see a magic mod that takes full advantage of the power virtual reality gives you.
Thus, my suggestion:
VRCANA.
This mod would be a magic mod whose progression system would be based solely upon exploration of the world, dungeon chests would contain a variety of scrolls (which could act like maps with words or symbols written on them) and they would need to memorize the words, shapes, or both, in order to learn the spells. Perhaps a spellbook could be added that would let you store the pages, and you could swipe your hand over it to turn the page to the next glyph or incantation stored inside, right clicking would provide an inventory that could hold about 20 pages.
Discovery: To gain the ability to cast the spells, you would need to find a stone circle (or build one) similar to Stonehenge, and physically sit down in the middle in order to "Meditate" and gain the power to cast the spells. We will call the power used Mana, though the name should probably be changed due to its overuse in other magic mods. (Non-VR players could crouch for the same effect.)
Each time you cast a more complicated spell, your mana pool will increase by a set number, capped at a specific amount (You could raise it further with equipment maybe?)
The only way to regenerate mana, is through meditation (and/or perhaps a bauble of some kind, magic robes, something like that) physically sitting down in the playspace and waiting for it to recharge. You will know if it is fully charged when your character model lifts slightly off the ground and you glow blue.
As said before, the spells will be found through spawns in chests in dungeons (Perhaps an addon for other dungeon mods to also have these spells in their spawn pool would be good) but they could also come in other ways, while you are digging around maybe you find a piece of stone with a glyph carved into it, and use some paper on it to take a rubbing, or a book with an incantation in it, and when you read it you tear the page you need out of it, adding it to your inventory.
Casting:
The actual casting of the spells would be fairly simple. Hold down the trigger with an empty hand (Or whatever casting implement you would add) and draw a shape in the air, speak an incantation, or both, depending on what the spell formula you found says. A circle could create a magelight, a triangle could summon up a blaze fireball, a swirl could conjure up a gust of wind to force monsters back. Really simple shapes probably wouldn't cost mana at all, these are called "Cantrips" like in most D20 based systems, and can be cast repeatedly without consequence, but are very weak. (Non VR players could pull this off too with a wand if it could check whether or not they are in VR and react accordingly)
The incantations would be a word, a phrase, poem, haiku, etc.
Example spell for raising the sun:
"Oh my solar sphere
One that shines ever brighter
I bid thee now rise"
Another example, this one to heal another while taking damage yourself:
"By blood begun, by blood undone."
The longer the incantation, the more powerful the spell. Incantations are tricky though, if you screw a long one up, all that power ends up discharging itself into you or your surroundings, so the really truly powerful ones would require some kind of ritual location to stabilize it and prevent you from killing yourself. Alternatively you could add an incantation or shape to cancel the spell you are holding. Incantations could also work outside VR, provided the other person has a microphone.
Another downside to incantations is that they use a lot more mana than shapes, so you can draw shapes while speaking the incantation to change how it works or maybe make it cheaper.
A shield shape while speaking an incantation could protect you from any magical backlash (Although it might take a chunk out of the environment around you)
A circle shape might change it into an AOE spell.
So on and so forth.
Custom Casting:
Lastly there could be a custom spellcasting system, where you somehow log a specific shape to a spell or incantation. This would be something only a powerful mage could pull off, as you would be squeezing a lot of mana into a far smaller matrix than usual.
Another thing you could do for casting spells on the fly is creating staves that you could infuse with a spell through a ritual. The staff could then cast a number of casts of that spell before needing to be re-infused, the better the staff, the more casts you get. A simple gesture like slamming the staff into the ground, jabbing the staff forward, or swinging it in front of you could activate it.
Last thing you might try for casting on the fly that could also help allies without VR, is spell scrolls. Infused through the same ritual as the staves, the scrolls are activated by a simple right click (Bonus points if each scroll's incantation was read out via sound file) and can be used by people without VR. Scrolls only work once, before they are destroyed, but you could try making a scroll bag, which could work like the Brew Bag from Witchery, or the AM2 spellbook, storing all the scrolls for later use.
Conclusions:
I have no clue if this mod idea is even remotely possible, but if anyone is a skilled enough coder to do it, it would change the way modded minecraft is played. Virtual Reality servers with magic duels. PVP worlds where wizards hide away as much of their knowledge of incantations as possible. Pancake players working alongside VR players, providing the services of the mods VR players can't easily use in return for their powerful scrolls.
Those of you who have VR headsets would know about the mod Vivecraft, even those of you without knowledge of this excellent mod would be aware of it from various youtubers and such (Especially because being a youtuber seems to mean you just get handed a free Oculus Rift S if you so much as mention VR one time).
For those who don't know, Vivecraft is a mod which makes the Java version of minecraft playable in roomscale Virtual Reality. for the HTC Vive and Oculus Rift headsets, seeing how far we have come in modding has been incredible to say the least if a mod like this even exists.
The downside of course to playing with Vivecraft is that there are a few mods which do not work well in Virtual Reality, and while the creator of Vivecraft is working hard to make a few of these well known magic mods compatible with Vivecraft, I would like to see a magic mod that takes full advantage of the power virtual reality gives you.
Thus, my suggestion:
VRCANA.
This mod would be a magic mod whose progression system would be based solely upon exploration of the world, dungeon chests would contain a variety of scrolls (which could act like maps with words or symbols written on them) and they would need to memorize the words, shapes, or both, in order to learn the spells. Perhaps a spellbook could be added that would let you store the pages, and you could swipe your hand over it to turn the page to the next glyph or incantation stored inside, right clicking would provide an inventory that could hold about 20 pages.
Discovery: To gain the ability to cast the spells, you would need to find a stone circle (or build one) similar to Stonehenge, and physically sit down in the middle in order to "Meditate" and gain the power to cast the spells. We will call the power used Mana, though the name should probably be changed due to its overuse in other magic mods. (Non-VR players could crouch for the same effect.)
Each time you cast a more complicated spell, your mana pool will increase by a set number, capped at a specific amount (You could raise it further with equipment maybe?)
The only way to regenerate mana, is through meditation (and/or perhaps a bauble of some kind, magic robes, something like that) physically sitting down in the playspace and waiting for it to recharge. You will know if it is fully charged when your character model lifts slightly off the ground and you glow blue.
As said before, the spells will be found through spawns in chests in dungeons (Perhaps an addon for other dungeon mods to also have these spells in their spawn pool would be good) but they could also come in other ways, while you are digging around maybe you find a piece of stone with a glyph carved into it, and use some paper on it to take a rubbing, or a book with an incantation in it, and when you read it you tear the page you need out of it, adding it to your inventory.
Casting:
The actual casting of the spells would be fairly simple. Hold down the trigger with an empty hand (Or whatever casting implement you would add) and draw a shape in the air, speak an incantation, or both, depending on what the spell formula you found says. A circle could create a magelight, a triangle could summon up a blaze fireball, a swirl could conjure up a gust of wind to force monsters back. Really simple shapes probably wouldn't cost mana at all, these are called "Cantrips" like in most D20 based systems, and can be cast repeatedly without consequence, but are very weak. (Non VR players could pull this off too with a wand if it could check whether or not they are in VR and react accordingly)
The incantations would be a word, a phrase, poem, haiku, etc.
Example spell for raising the sun:
"Oh my solar sphere
One that shines ever brighter
I bid thee now rise"
Another example, this one to heal another while taking damage yourself:
"By blood begun, by blood undone."
The longer the incantation, the more powerful the spell. Incantations are tricky though, if you screw a long one up, all that power ends up discharging itself into you or your surroundings, so the really truly powerful ones would require some kind of ritual location to stabilize it and prevent you from killing yourself. Alternatively you could add an incantation or shape to cancel the spell you are holding. Incantations could also work outside VR, provided the other person has a microphone.
Another downside to incantations is that they use a lot more mana than shapes, so you can draw shapes while speaking the incantation to change how it works or maybe make it cheaper.
A shield shape while speaking an incantation could protect you from any magical backlash (Although it might take a chunk out of the environment around you)
A circle shape might change it into an AOE spell.
So on and so forth.
Custom Casting:
Lastly there could be a custom spellcasting system, where you somehow log a specific shape to a spell or incantation. This would be something only a powerful mage could pull off, as you would be squeezing a lot of mana into a far smaller matrix than usual.
Another thing you could do for casting spells on the fly is creating staves that you could infuse with a spell through a ritual. The staff could then cast a number of casts of that spell before needing to be re-infused, the better the staff, the more casts you get. A simple gesture like slamming the staff into the ground, jabbing the staff forward, or swinging it in front of you could activate it.
Last thing you might try for casting on the fly that could also help allies without VR, is spell scrolls. Infused through the same ritual as the staves, the scrolls are activated by a simple right click (Bonus points if each scroll's incantation was read out via sound file) and can be used by people without VR. Scrolls only work once, before they are destroyed, but you could try making a scroll bag, which could work like the Brew Bag from Witchery, or the AM2 spellbook, storing all the scrolls for later use.
Conclusions:
I have no clue if this mod idea is even remotely possible, but if anyone is a skilled enough coder to do it, it would change the way modded minecraft is played. Virtual Reality servers with magic duels. PVP worlds where wizards hide away as much of their knowledge of incantations as possible. Pancake players working alongside VR players, providing the services of the mods VR players can't easily use in return for their powerful scrolls.