Karthus with Clarity? he has an ability passive that gives him mana back for minion kills...Defile's Active shouldn't be used constantly early game, the mana cost is too high: hence your mana problems...rethink your farming style and you will be able to replace clarity with something else more useful

You've made Wall of Pain a dump skill? do me a favor and read what it does. *waits* I'm sure you're confused as to why I brought this up...It will allow you to slow the enemy (making dodging difficult) and use lay waste to DPS them down (the MR reduction will reduce their MR to around 0 making your lay wastes do a lot of damage).

How many single-target, damage-dealing abilities does Karthus have? ZERO. Replace the rylai's with a rod of ages: 15% slow isn't worth the extra gold and reduced bonus health and AP.

Your runes are completely wrong...you need 3 quints, 9 marks, 9 seals, and 9 glyphs...not 18 marks, 9 seals, and 18 glyphs...

i dont understand why ur rated so low looks good to me maybe you need to add better detail to order of items

fixed the wall ranking up thanks for pointing that out

Terrible...

6 ranks wall, missing runes, late rabadon's, deathfire.