@RIOT My Objective Opinion on the Veigar changes
First off I love pretty much every rework so far , they all look solid and fair while also solving all the problems they were intended to solve. Congrats RITO! Now on to the little guy: I'm fond of the new Passive both thematically and gamplay wise. It makes Veigar more than just a Q farm bot now and he is gonna want to actually trade in lane now. Also his old Passive was indeed a big excuse for his super high mana costs, and I'm glad it's gone; I'm intrigued though as to why you decreased his mana costs by so little. Live Veigar's full Combo (E,W,Q) takes up half his mana , and If Veigar is gonna wanna look for Q poke to get stacks of his passive , he is going to drain his mana rapidly. I don't think 20, 10 and 10 less mana on his q,w,e respectively is going to make up for the loss of his passive. One last thing ;As much as I will miss nuking AP threats like a kat who just jumped in : BOOM ULT=> DEAD ( one shot) , I have to admit it wasn't healthy and it needed to go.
BUT since you removed the enemy AP ratio, i think that the numbers are very low... hear me out: Live Veigar wants to use his ult on an AP target to make the most of it, and potentially remove them from the fight. IF there are no AP threats he is going to want to use it on another carry , possibly an AD carry, but it won't one shot them and they are very hard to reach. So you probably are going to use it on a big frontline threat to burst them down quickly. But Mr cuts the dmg in half so he is not going to make much use of it. in general veigar is very weak if there are no AP threats for him to nuke.
So, what you are doing now is making his Ulti not only no longer have enemy AP ratio, but also do less damage straight up? His ultimate will be worthless then, aside from finishing off someone caught in your cage , WHO IS NOT A TANK. you really need to look at his Ulti numbers, the number you have for below 33% HP are far too low to make his ulti meaningful in any other way aside from a conditional execute ( conditions from enemy MR) That's all thanks for those great reworks !