Pros:

- It has the fastest clear speed of the jungle monsters
- Very healthy clear
- Huge amount of dps throughout all stages of the game
- Global pressure
- Strong duelist
- Fits in pretty much any team composition
- Strong sidelaner
- Scales really well

Cons:

- Immobile champion
- His DPS is very reliable on skill shots
- You need to practise his clears in order to optimize them
- Weak vs high ranged compositions
- Weak vs invade junglers
Summoner Spells/Runes

Introduction:


Now that you know the spells, runes, items,which champs are good against/with karthus and which abilities you'll skill it's time to teach you how to actually jungle on this champion.

Jungle clear:


The jungle clear on this champion is it's most powerful tool, to do it 100% efficiently you're gonna have to kite jungle monsters.
But it's more than just spam your abilities on the camps, to be 100% efficient, you must always use 2 Qs and 1 auto, repeat this pattern always in order to clear it as fast as possible.
You always start on blue side and you always full clear, ALWAYS.
This takes a bit of practise to achieve, so go to practise tool and if you're commited to it, feel free to check my vods on twitch aswell if you need to see it being done.
You have optimized your clear once you achieve full clear in less than 3 minutes with leash.
Win conditions:


It's very important that when you play a champion you understand what will make it win, luckily karhus has quite a few.
The most important one is to play around objectives, such as drakes/baron.
Due to his high dps nature, he can bring down objectives really fast in comparison to most champions which really enables your team to simply just rush them if the enemy team is lurking around the map. Fighting in closed locations is also very good since you have AoE damage and can hit multiple oponnents in fights.
The second win condition would be to play for sidelanes with your ultimate, or you can do it yourself aswell, karthus is a good duelist, obviously he's far from being the best, but he can handle himself vs a couple of champions specially if he's ahead.
If you find it hard to coordinate with your team to play sidelanes, which sometimes can be very frustrating in soloq due to the lack of communication, just group and fight it out, in the end, it's what karthus does best :)