what numbers are you using? his Q at max level does 50 + 60% AP and 90% AD and then third cast: 100 + 120% ap and 180% AD
it's also only an on-hit effect, so he's functioning at the same attack speed as normal
in addition, the AD value scales up, starting at 50/100 AD
let's say he has a trinity force, he can apply this at most 4x and of course his ultimate is very effective as a finisher but does a decent amount even when used as an engage , it would be a 6 second engage minimum and he has no gap closers or movement speed boosts
let's say he can somehow extend it perfectly and gets to use all 4 procs, he gets 4 auto attacks for their damage (that's quite a bit of damage for anyone), all 3 procs of Q (which you basically want to avoid anyway), his E damage and his ult damage
even at level 18, this is 146 x 4, + 292 * 4 + 200 + 360% AD + 240% AP + 155 + 60% AD + 60% AP and then percent max health on ultimate
let's say this is level 11 since you say two items, I don't know mordekaiser's ability path but let's use max Q since it seems to do the most
104 minimum AD x 4 + 208 x 4 + 200 + 360% AD + 240% AP + 125 + 60% AD + 60% AP and then percent max on ultimate
416 + 932 + around 360 + 125 + 60 = 1893 before defenses and that's not counting that he can cast his E twice in that six second window
#He is strong, but you let him hit EVERYTHING. he doesn't 80% for one Q...ever. He is also a juggernaut...you're not supposed to let them get near you...EVER
Any champion that you let them use everything and hit with trinity force is going to hit you very hard
#here's Aatrox: 4 x 103.9 + 4 x 207.8 + 393 + 421% AD + up to 100 + 80% AD
aatrox's ultimate increases his AD by 25% for 10 seconds
just from the above, 415.6 + 931.2 + 393 + around 432 + 100 + 80 = 1939, not factoring in ultimate or E value
both champions have conditional damage and if you rush in without prepping in some manner, they will probably crush you
#darius can do similar and true damage: passive: 115 + 150% BONUS AD (WHICH DOES NOT COUNT THE DAMAGE FOR EACH TICK OF HIS PASSIVE BEFORE HE GETS IT FULLY STACKED) (and I don't even know how to factor in his SECOND PASSIVE) + 4 x 107.9 + 4 x 215.9 + 160 + 140% AD + 50% AD with one point in W + 25% armor penetration on E
and then he gets 400 + 150% bonus AD as true damage
this comes to 433.6 + 867.2 + 160 + 140 or so + 53.9 + 400 = 2053
In fact, given the difficulty of landing mordekaiser's damage AT ALL, HE SEEMS RATHER UNDERPOWERED IN COMPARISON but is compensated by his ultimate's capabilities
if there's any issue, it's trinity force, but without trinity force, most champions that use it would have rather sub-par damage and they STILL HAVE TO GET IN RANGE TO HIT WITH IT