What are you building?
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Rotlai's Exploding Minion of Slows
Banner of Cohmmand
Tanky champ that has a zombie passive?
It's like a ranged Sion... I guess?
Your goal in teamfights is to slow everyone. EVERYONE on the enemy team. W has a wide berth, E is auto-slow. Q and R have so much ranged assist potential.
You can take Rift Herald, even if you die to it.
Gate with Rot, Promote Siege minions, Ohmwreck the enemy towers while you, Karthus, are with your creeps. Unless you're diving in a teamfight, then do it at that time >_>
Gold from both side-lanes (if you BoC top and Zz bot) while you **** around mid allows for so much pressure. And you can assist in kills, ganks and counter-ganks. Rylai's and your no-miss final smash can help a teammate in a pinch.
I look forward to tests.