Just gonna drop this here bc I'm sure there's gotta be another person who stayed up all night doing this too. Mind you this is all heavily opinion based, this is just the way I see it but you know flavor your pc as you will
DND STUFF (This can actually work.)
Battle Boss Veigar inspired
Step one: Make a gnome (scribe preferred for the early +2 to int)
With the alignment being chaotic good (despite veigar in lore saying he's evil he does more good than harm. Whether it be by accident or just to talk big fire)
Your stat array should have your int near maxed followed by your charisma then DeX. Veigar is neither very tanky nor strong. (He skips the gym but will always visit the library)
You mostly want to chose the wizarding class you think can lock ppl down the best I'm choosing graviturgist only bc 1. It's new and 2. Veigar commands celestial dark magics. That can be very cc based and help out his team
What I like to do first is pick spells that can slow or dampen enemy movements like grease, hold person, snare, ect.
Leveling up as you need to fill out all the little check marks of being a small tiny terror. What I found is once you get your int to 20 there is a way to get to 22. Mainly by 2 feats.
Linguist (which gives you +1 to int and 3 additional languages so you can spit them fearful word so they know how "evil" you are)
Then there is the other which is
Keen mind (You can clearly recall anything seen or heard within a month, you can determine north, you know when sunrise and sunset will happen, and gain +1 to Int)
This should put you somewhere around 22.
Ask your dm for some in particular items being the manual of intelligence or time of clear thought for an additional +2 int and once again raising the cap and you should be at 24. (But wait there's more!)
Get a staff of the war mage or make one following the guide to crafting items (same can be done for the smart book) and add a +1,2 or 3 to your spell attacks depending on the staff you make. By level 20 you should be somewhere around here
Also during this time you also want to naturally raise that charisma and take on the magic instead feat for that eldritch blast and that 1 other extra cantrap and free 1st level spell.
Not to mention being like this is so ridiculously strong if you should get into a scuffle in wide open space it should be pretty easy to nuke an grouo of enemies or hold them so your party can demolish them. Oh also did I mention your a gnome? Hiding and avoiding sight is a big part of striking terror and with your charisma it should be fair game or an average chance to scare someone.
Also if your dm allows pick up maybe 1 or 2 rings of spell storing and craft yourself some extra spell scrolls to really let loose your arcane might.
Also I'll just leave there here and y'all tell me if y'all like it if ya want me to make more how to posts and if you want me to try and make something for you.
https://m.youtube.com/watch?v=cmOWdbEiYr0