So.

You are trying to cure his level 1-4 game by rushing an item that you won't get till level 5 or 6.

Okay, i'll just turn that down vote into an up vote.

Start with regrowth, THEN get Revolver, immediately build into WotA, then build another revolver for a cheap 45% spell vamp.

Now, you build your resists.

A frozen Heart, and a Force of Nature, along with an Abyssal Scepter gives you 180~ of both resists, a large amount of damage, and 45% spell vamp.

Turn the revolver into a gun blade as soon as you feel that you have enough resists to survive the initial burst of team fights, then you have 50% spell vamp, a large amount of damage, gunbade's slow, and a fairly hefty tank.

I "insult" your build because it has major flaws, that's the only reason.

I disagree completely.
Mordekaiser does not need enormous burst damage, he has ghosts for that.

Mordekaiser scales excellently with flat AP runes and a rushed Hextech Gunblade, while maxing out his E enables him to hit minions, absorb shield, and then harass enemy champions with his abilities and main attack while letting the shield absorb the majority of the damage.

The point of rushing the hextech, is that his abilities use roughly 30% of the base damage they put out (50-100 hp per ability). By starting with a regrowth pendant, you are only recouping one ability use every 15 - 30 seconds depending on level. With 20% spell vamp and an ever-increasing amount of AP, Mordekaiser's abilities have 0 cost by the time you get your Rylai's Scepter completed (item 3 / ~level 12 / ~20-25 minutes).

The point of playing Mordekaiser is to draw the enemy team's attention in hopes that your AP and DPS will drop on their main champions while you target your favorite with your Ultimate to become the puppeteer. During all fights I initiate with my E, giving me 100-XXXX shield (varies depending on level and number of targets hit), I Alt+W to self-cast my shield which deals 50-200 DPS and refills my shield every second, and I use my Q to follow up.

You insult my first build without trying it out while I offered the proof of the amount of carrying this Mordekaiser build style does. You are looking at numbers while ignoring the AoE DPS of his W, the amount of spell-vamp (works on every ability, DoT/AoE W included), and the main point that Mordekaiser's most effective ability for is his ability to control the enemy ghost.

So, flat cdr seals, an amplifying tome to start, and ap glyphs?

Why so much flat AP when morde has terrible ratios, can't harass effectively, and practically needs hp/5 to not have an abyssmal early game?

You have ~80 more armor than magic resistance, and the thornmail is useless unless their AD carry decides to attack you. (In which case you've already won that fight)

That is aside from the fact that you do very little damage for how much tank you have.

Have to -1, build is basically a mash up of half decent items for mordekaiser.