Overview
If you ever thought that new champion kits are bloated and can do too much, well, you're not going to like Zaahen. He's a champion with mobility, sustain, CC, damage, and even a built-in revive. A product of modern League of Legends, Zaahen is a pick for anyone who wants the ability to carry, especially from top lane. You can check out our full page on him here, including all of his builds and how he does in ARAM, ARAM Mayhem, and more.
Keys to Remember for Zaahen
Much of your kit's strength revolves around being able to fully stack your passive - not only do you do more damage with it, you gain access to your revive, which will either revive you or give you a 5 second window to beat down your opponent. This means you want to commit to all-ins with him, as you can turn even 1v2 situations in your favor as long as you can finish stacking your passive.
For team fights, you can provide a lot of damage thanks to Grim Deliverance [R], and even if you aren't able to fully stack your passive, you can play more as a nuke and pseudo tank thanks to the sustain on your ultimate. You're more likely to play a disruptor, but if enemies ignore you and allow you to stack your passive, you can easily clean up fights.
Strengths
To be frank, Zaahen is a champion that launched with a 50%+ win rate, which is pretty absurd for new champions as it typically takes times for players to become accustomed to them. He doesn't have any glaring power troughs between early and late game, which means he's always going to have pressure. This combined with CC, a built-in revive, sustain, and a ton of damage makes him a huge carry threat from top lane.
Weaknesses
His passive's max stacks is at 12 attacks, which is a lot of auto-attacks that you're going to need to land to get the most out of it. Enemies are typically going to prevent you from being able to do that in team fights in particular. He does, however, need to have this passive up before he's able to cash in on his revive -- this means there's some risk and counter-play at the ready.
Game Plan
Early Game: You want to avoid short trades with opponents -- the ideal situation is to force a full commit so you can make use of your passive. Commit to the fight!
Mid Game: At this stage, you'll have a lot of side lane pressure when it comes to duels, especially against other melee champions or immobile mages. Team fights are going to rely on you hitting a big ultimate to find immediate value, otherwise you may find yourself kited to death.
Late Game: The plan is similar to the mid game -- side lane control will be key for you unless you're confident in your ability to fully stack your passive in a team fight.

