I have played 300+ games as malzahar and this is what i have to say
Nerf him. Hes my main and i want him nerfed. Ok, here is my go to build. every single part of this build is what i build assuming the game is going normally. http://leaguecraft.com/builder/malzahar/?items=75,7,18,84,94,116&runes=11,11,11,11,11,11,11,11,11,120,120,120,120,120,120,120,120,120,98,98,98,98,98,98,98,98,98,34,34,34&level=18&masteries=004110310013003103010000000000000000000103031000000000000&skiller=qeewereqeqrqqwwrww&fspells=true
The only thing that changes is sometime i do liandries instead of void and abbyssal instead of zhonyas, based on situations. Now, here is the damage output of this build. q: 834.85 w: 14.68% max hp per second e: 854.58 over 4 seconds r: 1418.7 over 2.5 seconds
please note that this is not with any dragon buff baron buff or elixer or the 3% from the final attack mastery. for the sake of arguement, we will assume that the e and r do the full damage as the only way to stop e is zhonyas which you cant do while he is ulting, and r can only be stopped if he is cc'd, namely hard cc or a silence. total output of combo: 3108.13 + 14.68% max hp per second
now. lets say you have 2.5k hp and 150 magic resist at the end of the game. typical adc/mages will probably have less but tanks/fighters will have more so we will call this a happy medium 150 magic resist -29 from boots and runes = 121. -35% from void staff 78.65. now. rounding up 79 magic resist is 44% damage reduction. ok, so assuming he does his combo and you get off the pool the MOMENT his ult ends via flashing or some other way (we will count the e damage as complete at this point as you cannot get rid of it) 3108.13 - 44% is 1740.55. already we are at less than half hp. now his w. 14.68% of 2.5k is 367 exactly (wierd i know). so 367 damage x2 seconds (rounding the 2.5 sec ult down) is 734. -44% is 411.04 1740.55 + 411.04 = 2151.59 now you might be saying "well he didnt kill you right? haha no malzahar runs ignite. ask anyone he just does. level 18 ignite is 410 true damage. magic resist does nothing. 2151.59 + 410 = 2569.59. you died. Now, this is very close. we just barely broke 2.5k hp and 150 magic resist. Of course, this is assuming you have full hp as well, which might not always be the case, but as well we are assuming you have no shield from say bloodthirster or otherwise.
But you might be saying "my teammates will save me before this ends" i want to remind you that this is in 2.5 seconds. having a malzahar is the ultimate scare. You think rengar makes bushes scary? try a malzahar.