Recently in our gaming group myself and one other PC seem to be doing all the "legwork" now normally I dont mind shining but I feel I need to make a change.

I was playing a level 6 Magus, I felt over powered in the last few sessions, it became fairly apparent that me and other PC Human Ranger (Archer) were just demolishing standard encounters (We are playing through the Kingmaker path, on the second near the end) He did close to 115 damage one round and I pulled nearly 70 at one point on a Empowered Shocking Grasp crit with the scimitar.

The DM has NOT asked us to change and is considering 'beefing' the monsters up, I kind of feel its unfair to beef them up where the other players who arent doing nearly as much as me and the other PC are concerned. Its not fair to them, the only really fair option is to bring us down/play something less 'flashy/omgdestructive'.

Now I dont know the ins and outs of the Ranger character, nor do I know his math or how hes calculated. But from what I 'know' of Archer Rangers it seems legit.

So we discussed at the end of the recent session about how to handle this situation. Do we bring ourselves down to the level of percieved power of the other players. Do we help them 'optimize' and bring them up? Do we just let the DM 'beef' the ecounters up?

TL;DR - I have decided to bite the bullet and change up MY PC for the sake of the other groups fun. My request to those interested is to help me build a decent "ARCANE" caster (They have none, only a multiclass bard) that can get decent bang for its buck and help the party at large to the point of being indispensable, I am the Magister for the Kingdom.

Now; I have been looking at the Witch, Sorceror and of course the Wizard. I am not sure which to go with, any help on level by level breakdown of builds up to 7, beyond for extra credit would be wonderful. I am normally decent at figuring these things out. I have looked through the various guides and have a general "gist" of how to work it but I wanted to see what you all thought.

Party consists of Ranger7 (Archer) Human, Rogue7 Human, Bard5/Oracle2Elf(? Though shes been shapechanged into a DM snake-like humanoid creation)
Fighter (TWF) 7 Human.

Also DM/Group doesnt use AOOs at all. Which is why im leaning to a caster.

Thanks for your time and effort, should you choose to help a brother out.