I've been having trouble with Morganas as Karthus when mid landing. Her spell shield shuts me down and tormented soil doesn't allow me good positioning to farm.

Also, I run out of mana consistantly at all stages of the game. Anyone have a build that has mana regen/max mana boost without sacrificing that much damage?

How to not run out of mana on karthus: Put one point in your E at level 2, and then last hit minions.

As to laning against morgana: Dodge her Q and don't stand on top of her W. Easy, done. You're a far stronger hero than she is late game, so you shouldn't be trying to kill her anyway.

Don't face Morgana as Karthus, she counters you and that's on of the matchups Karthus doesn't win. You have to outplay her throughout the lane phase.

Boots to start, will help you dodge her q

My first item is a tear. Followed by RoA

Morgan's works by soiling under all 6 of your minions, but if you can drop her first line of minions, yours will move off her soil and it's wasted.

Black shield has a longish CD, also be patient, outfarm. Roam.

You could also place your wall so that she'll have to walk through it to farm

I play morgana a lot. You win in lane vs karthus, but. 1. His q is extremely annoying. 2. It is kinda hard to outfarm good karthus. 3. Often they play with TP so u can't get a kill either. At least not easily. 4. After 6 his has great global presence, while you have to choose whether to roam or play safely. That ******* will het kills for free, anyways. RRRRR. 5. Lategame morgana is 0. No, even -1. Karthus is dps monster.
So, it really really depends in team comp.

All I have to say about Karthus.
If you can't actually out harass your lane opponent, forgetting about harassing them and just farm. Keep out of their range if you can and stay at turret.

Building a Tear of the Goddess after you finish Catalyst is a decent idea for any mana issues you might have, but it really shouldn't be a problem if you last hit with your q after you put a point in e. Sorta like Annie I guess, unless your going in for the kill you shouldn't be going oom.

Just farm with your Q, get RoA to keep your mana up, make sure you get blue buff. Your karthus, dont worry about killing her, since its very difficult w her spellshield. Just hit R and get kills across the map. Make sure you dodge the Q or youll die. Just sit back, farm up, wait for jungle ganks and hit R

I don't play karthus but I do play morg and this seems like pretty good advice. Morg isn't really able to kill somebody herself unless she can land Q or flashes in to ult. Her Q is only of the slowest skillshots in the game and it's blocked by minions so you really shouldn't be getting hit by it unless you're being lazy. If she flashes in to ult you then you flash out, that's the reason you took flash isn't it? Also remember to ward so you don't get ganked by the jungler, Morg is able to support jungle ganks really well and karth doesn't have a natural escape.

Otherwise you just want to try to stay even with her farming. Morg farms really well but Karth farms pretty well himself and will outscale her late game. So if you stay even you're technically winning when you think about it. You're not really going to be able to get kills on morg early unless she's dumb, she's a really safe laner, that's one of her biggest strengths.