Recently purchased 
, and I've been enjoying him a lot. However, I've been in a sort of in between of feeding and carrying while playing him, resulting in two losses so far. I'm just wondering what I can do to lower my death total while still keeping my kill and assist ratio high.
if you die make sure you're useful before/after your death he's got that juicy passive after all
slap your wall across a choke, force the enemy team to make a choice, flash into that choke, turn on your e, zhonyas, then sit there and q until you die, then ult, then q until you actually die.
farm farm farm, when you push lane too far, go farm the raptors in the jungle.
if needed sacrifice yourself for the team.
even if u die u can fight with team in a 5v5.
During his passive, after he dies, Karthus has (unless I am mistaken) enough time to cast either three, or four Q's. Or, 2 Q's and then his Ult. To that effect. I find this useful to keep in mind when I want to deal dmg after I die but want to be able to have enough passive time to cover Ult's casting time. Otherwise you have to wait until you revive before you can ult. Not the summoner revive, death timer. Also, Rylai is very good on him, and practice on hitting 1 target with your Q. 3 caster minions in a line? Ok put a Q off to the side and hit 1 Minion with its radius. Practice single shotting minions in a wave in bot games and take it to pvp, you'll find your dmg out put per mana cost expendeture (or some word of that nature) to be more efficient.
