hi guys I'm looking for a fic in which twilight was insanely powerful as a filly. Any recommendations?????

Try The Moons Apprentice , It's an amazing story in my opinion.

Or maybe The Monster in Twilight

Got a few but some come to mind mostly for what your thinking.
https://www.fimfiction.net/story/196256/the-moons-apprentice
The Moon's Apprentice as lulianDan says is brilliant pretty much nightmare moon takes twilight as a pupil when celestia believes her magic is too dangerous.

https://www.fimfiction.net/story/407713/in-the-land-of-twilight-under-the-moon
Another good one in my opinion is In the land of Twilight, under the Moon as its about twilight almost dying during the entrance exam but ends up merging with a alternate timeline version of herself giving her control of the stars much to celestias bewilderment its a good read but still waiting for a update.

Theres also Twilight gets a Puppy https://www.fimfiction.net/story/384960/twilight-gets-a-puppy which is a full retelling of mlp with lots of au elements with twilight summoning another being when doing the entrance exam along with spike and a similar but very different story unfolds as the characters are very changed by this event as most characters not just twilight get very fulfilling arcs and backgrounds but this is the longest so far as the linked story is season 1 while there are multiple seasons up to currently season 4 so its a long one.
Hope that's helpful I've got a addiction to this stuff :) edit sorry about the links am new at linking stuff

7330560
That is way too vague. Please be more specific.

thanks sooooo much for all the suggestions

are there any more?

7330582 A good percentage of the fics in this group's story list would fit. (I'm biased to Monster myself, but it has been going on *forever*)

This is my personal favorite OP filly twilight story
https://www.fimfiction.net/story/68954/homecoming

7330560
If you are strictly talking about filly aged Twilight theres:

Render Unto Twilight
Celestia's Tiny Student

I remember there being more but I lost the names I'm sure scowering the archives will bring up more but for now there are theese

7330560
Well it only starts when she is a filly but you might want to look up Twilight gets a puppy