please look at this:

here

lot of work to do...currently it is difficult to read. the red text makes me angry...and my eyes started bleeding.

HUE HUE HUE

Deathcap isn't great because of his **** ap ratios.

Liandry's is bad, Rylai's is bad, Randuin's is pretty bad, amp tome should never be started ever, same with that mr item, spirit wraith is an ok item in premades because morde is extremely good at farming both jungles if given the opportunity but is not great in solo queue and is fairly niche anyways, lichbane is extremely sub optimal, ohm wrecker is sub optimal (seriously?) wit's end is just terribad, w max is the best max atm for sure

your icons aren't icons, they're just pictures, fix that

colored text does not improve a guide

you're linking to the wiki or something instead of just putting square brackets around it which is much better

your main purpose is not to bully the laner, that used to be his purpose but for the first 10 min of the game morde is just a giant pos against most laners ever since his nerf

morde shouldn't really be laning a whole lot in solo queue because it makes him extremely squishy without shield up and he doesn't have advantage - try to set up bush ganks on the jungler, catch him out in his jungle, catch the support when she wards etc, because otherwise you will simply not catch anyone.

maxing q first is just worthless compared to e/w max, maxing it 2nd or putting 2 points in q and e early is acceptable

using ghost on ap carries or junglers is not worthless, not at all.

if a high threat is low like the adc than you can use it on them, 1 shotting them and using the ghost the quickest - but if you can 1 shot their most tanky team member they will likely be melted by the rest of your team because they no longer have a peeler.

morde's best phase of the game is without a doubt lategame but you have to know how to play him...set up baron fights and bait and he will shine a lot, same with splitpushing (generally)

do not ever take marks of ap, the only marks you want are either mpen or POSSIBLY armor.

Randuin's Omen > Frozen Heart, Will of the Ancients/ Hextech Gunblade > Spirit of the Spectral Wraith, Locket of the Iron Solari meh, Warmog's Armor okay maybe

Suboptimal, but abusable if given the correct circumstances.

Those Greater Mark of Ability Power are not really needed and you mention far too much situational items. For instance Wit's End, Spirit of the Spectral Wraith, Warmog's Armor, Locket of the Iron Solari or Frozen Heart are completely suboptimal ..