Flexible Magic

World-changing utility effects are undervalued in it, if you decide to take the route I did and try to examine how a society with supers in it would evolve.
I once made a character, as a white room exercise, who could create entire buildings for rather cheap, but only if you allowed created items to be fused together via the power (create one wall section, create the next attached to the first, so on).
I would suggest Are Magical, but as stated, M&M is good if you don't mind more cinematic games.

Would there any way I'd be able to implement """better""" comsic or colossal mass changing to the world?

No, not really. I had to make an entire setting for that, built from the ground up. Its pretty easily rationalized though: stuff like super tech can only be truly understood by tech focused supers, and so can only be replicated by them or by following a very specific process. The rarity of supers work against their ability to effect the world in a technological or magical capacity. In any case, it takes a massive budget to produce very limited quantities of super gear if you aren't a super. If we look at the MCU, the most common supers would actually be the sorcerers from Doctor Strange, and they are rare as fuck.
Trying to determine what changes a super leaves by the very presence of their powers is an autistic thought exercise, and thus not really worth brooding on unless you intend to create a new setting.

Well shucks, I've been wanting to do a "player shapes a plane" game for a while but I can't figure out what system has such powerful magic.

Oh, I was specifically talking about M&M. For wold shaping... Depends on what sort of limits you want to put on, how much of a focus its supposed to be, stuff like that.
My suggestion? Pick a system, and write your own rules for that. If you don't mind FATE, Unwritten has that, but a lot of detailing is narrative between player and gm. A variant form stripped down to base mechanical concepts can be applied to any game though - player decides what aspect of their world to work on, rolls to craft it with good rolls allowing them more details to decide, then roll to implement. Each stage requires checking for contradictions, which would give bad things.
Does that sound like a good basis for you?

I'll check the thread when I wake up, it's 0230 here and I have nieces to watch in the morning.

Talislanta has pseudo-spontaneous magic. Your magic skills consist of a domain (pyromancy, crystal magic, divination, etc.) and various verbs, and you cast a spell by picking a domain and a verb and describing a suitable effect.

Fluff-wise though the spells aren't spontaneous, it's just assumed you always knew that spell, and you're expected to give it a name and such as if it were a pre-existing spell your character learned while training.

Ars Magica is definitely the gold standard for this kind of thing. It's got spontaneous magic with plenty of rules for resolving pretty much any effect, as well as formal ritualized spells, with extensive rules for creating them as well (a lot of the game is doing magical research and creating new spells, which you can record in spell books for future characters to use)

Do you mean on the fly or crafting them beforehand?

Most effects based systems (supers systems have been mentioned before, but Savage Worlds spell system works similarly) can handle the latter, and I would only try creating spells on the fly in very light, probably narrative systems, because otherwise it's going to end up in more time spent looking up rules than playing.

I've read a bit of Ars Magicka and stopped half way, it lost my interest even though it's very extensive.

I mean crafting them before hand. Systems like GURPS where I can build these abilities and fluff them (or choose pathways with fluff) would be nice.

GURPS, HERO, M&M, Savage Worlds, possibly Valor would be my recommendations then, roughly in order of complexity.

Valor? Haven't heard of it. And could you give me a run down on SW? I've heard positively of it, is it for making a quick action focused game that's tweakable??

Valor is sort of a point-buy D&D 4e, with heavy anime inspirations.

Savage Worlds is pretty much as you describe, a fast paced action game. It uses dice-steps as stats (so stats go from d4-d12, you start adding bonuses from d12 and up), and a system of traits and drawbacks to build characters. The spell creation system has you take some effects, pull a trapping over it (i.e. fire, darkness, whatever), and basically that's it. A bunch of fan-made "grimoires" exist for pre-created spells that can give you ideas how you can bend it further.

It's a fun system with a few things that you may find annoying, like the exploding dice mechanic.

Huh, what about settings that allow me to play eldritch entities battling through the aether?

That Dresden Files RPG, but it's also probably not the kind of system you're looking for either.

It may be a bit too low powered for that without tinkering/refluffing stuff, although I do remember a fan supplement with similar themes. Hell if I know what it was called, but I think it was made by the same dude that did Savage Armory.

It's also possible that a more narrative based game would be better for that sort of setting (at least it gives me vibes of a world with more "nebulous" rules than what SW usually handles).

I had a system where spells were crafted with runes. Learning even a single rune was meant to be difficult and require high INT but recombining and ordering different runes in a phrase is what makes the spell magical.

Do tell, was it homebrew?

Pathfinder has an alternative magic system called Words of Power that let you combine different aspects of a spell (range, duration, effect/element/etc...) into customized spells.

It's not particularly robust, doesn't technically work on a point-buy, but I figured you might own or already play Pathfinder, and it could save you the hastle of learning an entirely new system.

i see no reason why gurps isn't exactly what you're looking for, just keep it light on the optional rules start with gurps light and look at thaumaturgy.

Wizard World, which is a hack of World of Dungeons, an Apocalypse World hack.

Haven't played it, but seems like a decent conversion.

>apoc world hacks
>decent
Not even trying.

The Black Company. From Green Ronin. best fucking d20 magic ever. I know d20, gross, but the magic system is both simple and hilariously deep. Its fucking awesome

Desolation
You just pick a arcane /shamanen/... as a skill and every spell you cast is: you say what you want to cast and the DM says the difficulty and then you roll

It was sort of, yeah. I borrewed lots of rules from 5e, lightened up a bit, and replacing the spell and magic mechanics

I like GURPS's Ritual Path Magic.

Pathfinder Ultimate Magic
>inb4 autism
But honestly, there's a neat system that allows you to build spells on the spot.