Invent new Spells

Hi, what if I want to Lightning Bolt someone, 'cause I hate Fireballs?
Or do Evan's Spiked Tentacles of Forceful Intrusion^tm?
I mean, spells not covered by Ritual Magick (which IS useful even in combat, sometimes).
Is it more fun/balanced to change the color of a spell, or to tweak an existing one and add it to the spell book? Or SWAP it?
Say, i find the super - uber - pure - crystal of the tempest (magic item) and it teaches me the Lightning Bolt spell, which is like a fireball, but add stunned on a 10+ AND may bounce back on a 7-9 (or miss).
Couldn't find a topic on the forum; it seems very strange. Am I the only one?
I swear, I DON'T want to do a Magic Ciclopaedia, with 1.5k spells.

Making up new spells is an awesome idea!

Most spells don't have different effects on 7-9 vs. 10, so I'd think of lightning bolt as just a different effect than fireball. Stunning them seems likely, and there's always the classic area of effect vs. single target difference.

and, you can always create and learn custom spells through ritual.

Please can you explain "create and learn custom spells through ritual?"
How is it done?

Wizard: I'm going to use this place of power to craft a new spell.

GM: Okay, tell me about the spell

Wizard: Well, it's a bolt of lightning from my fingertips that strikes the creature it hits dead and can never miss.

GM: Hmm, okay, well the best you can manage is a lesser version: a 5th level spell that does damage like a fireball to one creature and stuns them momentarily. Drawing on the place of power gives you the raw energy, but you'll need a creature of electricity to aid you in the research. An elemental will be best, but even a few lightning-struck villagers will be fine.

+++Souldrain+++ Lvl 5
Nasty shadowmagic.

You can choose to either curse the target or do damage straight away. When your target dies, either if it was cursed first or dies from the damage from Souldrain, gain one Soul. Spend a Soul to heal yourself 1d4+1 or add 1d4 damage to your next Souldrain spell. Souldrain does 2d6 damage when used as a damagespell. As a curse, it lasts until end of combat and adds +2 to damage rolls against the cursed target.

It can be described as all the shadows around the target suddenly move into the target, then rapidly forms a bridge between the target and caster before returning to "normal". Shadowmages can also stir something that lives in the shadows with careless use of the dark arts.

And so, when I finish the ritual, I've got a new spell added to my book. It's not exactly what I wanted, but such is the way of mageshido. Right?

Thanks a lot!

GM: Hmm, okay, well the best you can manage is a lesser version: a 5th level spell that does damage like a fireball to one creature and stuns them momentarily. Drawing on the place of power gives you the raw energy, but you'll need a creature of electricity to aid you in the research. An elemental will be best, but even a few lightning-struck villagers will be fine.

Heh. And sure as sage is used as a smudgestick, the nearby village full of hero-loving villagers just happens to be full of potential candidates to 'aid' in the research... It also happens to be the hometown of the Fighter of the adventuring band who just so happens to  think that the Wizard is weak.

In addition, the cleric knows a thing or two about electrical elementals, worshipping the god of thunder and lightening after all. I wonder how she would feel if you asked her to petition her god to manifest an elemental to 'aid' in your research?

Could it actually be "electrical elemental" of varying duration?
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