Hi, i'm cruelbuddy, a mid-laner main. I'm here to show you how I play one of my favorite champion in the game : Karthus. I know he is quite underrated and not picked a lot in rank games, but if you understand how he work, he can be a late game terror. I've main him since mid s2 and i'm happy to share my knowledge of him c: .
Some people say that maxing (w) second is better since you have a nice slow and a better engage in team fight. Well i prefer maxing my (e) second since your (e )give mana if you kill an unit. So its better for farming champ like Karthus in my pov. Your (q) is the first thing you max since it deal tons of dmg late game. Your ult is pretty obvious aha. And your (e) then (w).
So early game, you try and stay in lane and farm as much as possible and rush a tear. Karthus main goal is farm and be a monster late game. Tbh, you can be 2/9/5 but if you farm a lot and have all your core item, you still hurt. Buy ward a lot because in my experience of Karthus, people tend to gank me a lot since I have no escape and cc except flash exhaust and wall. One of the most important thing with Karthus is to trade when the enemy harass you. So example, a Katarina harass me by going in closer, I try and (w )on her, then spam my (q) since she burned her spell to harass. She will receive more dmg and I win the trade. Last hit as much as possible. Shove your lane and back if you have around 1200~1600g. Farm wraith too if needed. For me, I get 80~90 cs in 10min so guys maybe aim like me c:. And normally, I don't ask for gank with Karthus since he is not a really good follow up to finish somebody (even with w and q, the enemy might flash away).
Okay so normally mid game is quite objective battle. Karthus is quite good since you can contest objective such as drag/baron with your aoe presence( wall/ defile / ult) and you deal double dmg with your (q) on drag and baron. He shove minion wave quite fast and has good team fight presence. Try and stay with a teammate to safe farm because if you get caught 2v1, well you're kinda dead :C. Karthus can zone for objective control such as dragon or baron and he can deal quite a lot of damage because of his (q).
Late game is where Karthus shine. Your ult full build does like 900 dmg to everybody, so use it wisely. Your (q) too does almost 600dmg single target AND ITS SPAMMABLE. So Karthus is like a dps ap. Try and team fight as much as possible since thats where he is strong. Pick up enemy if they are low with your ult since death timer is quite long and you might get objective. To pick up low enemy easier, ward up as much as possible. If you get caught, try and kite with your (q) and then all in if you think its safe (1v1 only). Contest objective too since Karthus can do a lot of dmg. So basically, do like in your mid game aha.
This is the most important part of Karthus : its his team fight. So Karthus does more dmg if he is in the middle of the enemy team, so try and be there. How you engage is that you try and land your wall, then rush in with your (e) and seraph on since they might focus you first. Use your hourglass when your low so your invulnerable then when your Hourglass is off, (q) the carry as much as possible. Usually, I rush in when I have my Seraph/Hourglass active. If its not on and a team fight occur, I stay in the back line with my (e) on, put a wall, and spam my (q). Then if I die, I land 1 (q) then ult. Your ult in this situation is not to ks, but to help your teammate to clean up.
So I think Karthus is amazing late game, but maybe for some of you his early game is hard or boring. He is quite hard to master, even i'm not a Karthus master. Well thanks for reading this and hope you guys learned something new about Karthus c: .