Put the Meta in Metamagic. Make spells feel uncanny and your players embarrassed. Material components, rituals, somatic elements: what if they were META? Extradiegetic? The in-game spells of magic-users can be boosted by performing ritual out-of-character actions. Once the out-of-character ritual has been performed the spell functions as written in-game, but with a powerful twist. Here are examples for the first level OSE spells.
1st Level
Give everyone at the table a piece of chocolate///the Charm spell can affect undead
Detect Magic
Intuitively, draw a sigil on a small piece of paper and eat it///Detect Magic functions via sight as normal but also Taste. While the sight detection ends after 2 turns, taste lasts for 2 hours. Taste magical things to comprehend their enchantments.
Floating Disc
Press yourself against the ground, eyes closed and mute for 66 seconds///the disc functions and moves as normal but can be commanded anywhere with the caster's line of sight.
Hold Portal
Hold a T-pose for 1 minute///for the duration of the spell the door cannot be opened by any means.
Quickly waft a lit match into your open mouth///Light radius extends to 120 feet or the target is blinded for hours rather than turns.
Snuff out a candle with a pinch///Darkness radius extends to 120 feet or the target is blinded for hours rather than turns.
Intuitively, draw 4, 6, 8, 10 or 12 arcane sigils on your skin using a permanent pen///in addition to your usual magic missiles, gain another magic missile that deals damage with a die equal to the number of sigils you drew. 4 sigils for d4, 6 sigils for d6 and so on.
Circle an egg around your head three times and then quickly dispose of it///The spell's bonus to Saving Throws and penalties for attacking creatures are equal to the caster's level.
Without stopping or speaking, furiously fill an entire side of paper with asemically written glossolaliac language///the first language you read you can speak for the remainder of the day.
Gouge out one of your own eyes and throw it into a natural body of water or well///Read Magic lasts permanently and functions across all future rpg characters in any system indefinitely.
Have a fellow player spit at your upraised, outward facing palm///Caster’s AC is improved: Against missile attacks: AC -2 [21] and Against other attacks: AC 0 [19].
Swallow any type of pill///this Sleep spell lasts for 4d4 days against a single creature who is rendered invulnerable and immovable for the duration of their sleep. It can affect any type of creature.
Genuinely make a fellow player turn to look at something that isn’t there///any sound that can be bodily produced: footsteps, the rasp of your drawn sword, your heartbeat, flatulence, etc can be thrown/ventriloquised.
If while performing any of these magical acts, the player wishes to shout or chant the name of the spell their character is casting - praise and reward them.
2nd level
Silently, hold eye contact with the DM or another player for 13 seconds///the caster may instantly detect the thoughts of an individual creature without delay.
Singe or burn a piece of cobweb///your character’s web now covers an area of 100 foot cubed.
3rd level
Burn a piece of your character sheet///the fireball’s radius is 80 feet.6th level
Kill a living thing///the Death Spell affects 8d8 HD worth of creatures.Go suck it B.A.D.D!