Why we cant choose Karthus?
one for all 
one for all 
Because his ult does 550 damage before counting his ap, and it's not fair for the enemy to be able to do 2750 damage to everyone.
Hes permabanned. I want to know why though.
You really dont know why?
You get enough AP, and the enemy doesnt build MR. You can just ult them to death without even being near them.
Even if they get a banshees 1 person can ult away the banshess and then the other 4 can ult tand kill them.
I assumed people would build MR against him. Getting far enough to kill everyone with a 5 man ult would take some time and gold tho, barely anyone knows how to effectively play karthus.
Yeah but not just the ult to actually. I mean look at how much damage 1 Karthus does in the middle of a team fight with Defile...then his ult.
Now you got 5 karthus all in the fight with Defile going and then ults popping once they die.
So even if the other team wins the teamfight the karthus team will still get a ace.
Too bad tho......i was sort of wishing they would make a All For One URF mode...........but if he is banned in reg AFo then he would definitely be in that.
you can make an "its op" argument about everyone, i guess karthus makes more sense then msot though
Is he permabanned now?
That is really silly lol, he wasn't when One for All first came out. I guess having the ability to ult all at once isn't the most fair but it was still super easy to counter.