So this is a build i use for classic mod(i wouldnt even use karthus for dominion) and it seems to work pretty good. now you will die often at start if your not careful but thats alright as long as you keep getting minion kills for gold. i find at start i try and get money fast and use lay waste often to build up the charges on tear of the goddess so by the time i buy archangels staff i have a decent sized mana pool. once i reach lvl 10 or 12 i try and push all lanes with defile to really gain exp and gold. once i get void staff and rab's deathcap i try and stick with the group as i can at that point do some serious damage if not kill a champ or two. by lvl 16 i can pretty much take on most if not all champs 1v1 or even 1v2 if their dumb enough to stay in defile even after i die.