Originally Posted by MilkJugg24
5 full archangels + rabbs
all ap per lvl runes
all offensive masteries
... 1337 AP = 1125 (+3343) Magic damage
I think I just one hit Galio...
You most certainly didn't 1 shot Galio, since you only have 10% MPen.
Also, he said with 1K AP, not whatever build you want.
Fiddle would deal 3270 base damage, plus 6.75 AP ratio to a single target in 5 seconds, which deals a total of 10 020 magical damage. His passive also means he has a little more MPen than any other mage, which gives him ever more of an edge.
That being said, assuming she hits her ult, hits with her E 9 times (it has a travel time, so you can't possibly hit it 10 times in 5 sec even at point blank range) and keeps her Q on for 5 sec, Cassiopeia would deal 2875 base damage, plus a 7.8 AP ratio, for a total of 10 675, which puts her OVER Fiddle in perfect circumstances (also remember that the Fiddle damage assumes he hits with Dark Wind 3 times the same target). That's without taking into account the -10 MR from Fiddle, but even vs targets with no MR, he would not deal more damage than indicated unless he gets help from Amumu or Soraka to shred their MR below 0.
Note that Karthus doesn't even come close to those 2 with his 6000 damage over 5 seconds to one target with 1000 AP. He does, however, have his MR shred on his wall, so that increases his dps of course.
Also, you have some fringe cases like Evelyn and Malzahar (6 warmogs target, for example) or Katarina (gets 5 kills in 5 seconds) who could top this off, but that's even more unlikely than hitting all your skillshots over 5 seconds.