I think Teemo needs a rework.
I love playing Teemo. I love playing him dearly, because I'm one of those sadistic bastards who likes playing the part of the ambush predator, who likes setting up traps, who likes keeping his opponent's at arms' length while slowly wearing them down. I like watching as someone's hopes of getting away from a fight with a sliver of health are crushed by stepping on a shroom and watching them contemplate their mistakes as their HP ticks to 0. I like bullying my lane opponents while remaining untouchable.
... So why's he so bad at it?
Honestly, Teemo isn't in that bad a spot right now, but he's very... niche. And by niche, I mean "he's only good against this one specific kind of champion". Toplane winds up with a whole lot of different champions mashed together - Tanks, Juggernauts, Skirmishers, Fighters, and poke champs all wind up against Teemo, and Teemo's only really any good against Juggernauts. Tanks like Mao'kai can just ignore Teemo's poke because they're going to have a way bigger teamfight impact than him, even if he gets fed, so laning phase doesn't matter that much (hell, some of them even have better early-game burst - I'm looking at you, Ornn). Duelists like Riven or Divers like Camille often have way better damage than him AND better defense, along with reliable ways of closing the gap on him if he tries to poke them. It's usually a skill matchup but a good Riven player will beat a good Teemo player every time (not that this is a bad thing). Even against other poke-friendly champs like Jayce, Teemo loses because Teemo's poking power is really all he has and he loses out against someone who can do it better. The only class of champion Teemo can reliably produce results against is a Juggernaut like Garen who doesn't have a reliable way of closing the gap (and even then, there's Nasus or Trundle who have long-rage slows and can just run up to Teemo and beat on him until he dies without really caring about his blind because there's no way he's getting away in 2 seconds without burning flash). And then, when he is in that favorable matchup, he's completely infuriating to play against! There's no way to play around what he can do if you're stuck in that matchup and then you're stuck playing toplane misery simulator 2018 for the next 15-20 minutes. The only time Teemo's not getting dumped on is when he's making someone else miserable - so this isn't really me complaining that I want Teemo buffs. This is me complaining that I want a Teemo rework, because his kit is unhealthy.
The first unhealthy part of Teemo's kit is that he's a champion who can only ever punish mistakes instead of make plays. He punishes people for staying within poke range, punishes auto-attackers for going in, and punishes mistakes in positioning or being predictable with damage from his mushrooms, but almost nothing he does can make plays happen besides flash-ignite. Even Singed, another champion who's exemplary of this, can run in, flip a vulnerable carry into his team, and peace out while everyone is trying to figure out what just happened. Teemo has almost no outplay potential. While I think it's important that he remain an easy-to-play champion like Warwick was before and after his rework, a little more depth to his kit would be appreciated, and would better prepare people to take on more mechanically-intense ranged champions like Lucian or Vayne.
The second unhealthy part of Teemo's kit is that he doesn't really sell the "ambush predator" vibe to me anymore. He's not especially good at ambushing people- His passive is good for that, but the rest of his kit is for quick trading with AA champions (Q), keeping melee champions at arm's length (W), sustained poke damage (E), and... warding (R). He doesn't have the same amount of burst an assassin would have- in fact, if he takes an assassin by surprise, it's usually the assassin that'll kill him anyway! He's barely encouraged to play like an ambusher or a trapper, and instead he just litters his mushrooms around the enemy jungle (or his jungle, if he's losing), hoping to either annoy the enemy team with a couple hundred damage before a teamfight or catch out a fleeing enemy with very little health.
He also doesn't really fit into any of the roles in the metagame. He's okay at pushing, but he's not a good split-pusher because he really can't afford to get caught out like Tryndamere or a Duelist champion. He's notoriously awful at teamfights, too. He's good at poke damage, but only in toplane- Once teamfights roll around, if he tries to poke he'll get caught and summarily murdered (along with possibly the rest of his team). His single-target damage can't be likened to an ADC's because his E takes too long to process all its damage. If he tries to use his passive in a teamfight situation, he's probably just going to get focused the moment he reveals himself (if a stray sweeper doesn't point him out first). Worst of all, he takes up a team slot that could be used by someone with more teamfight utility, instead of a squishy little yordle who needs peel. His wiki entry lumps him in a group called Specialists along with the likes of Azir and Heimerdinger, whose strength is supposed to be area-control, but his shrooms aren't even particularly good at that- Essentially, they're just short-range vision wards that go away and hurt a bit when you step on them. They don't command the same amount of respect as Azir's soldiers or Heimer's turrets- especially because it's very, very easy to make them go away by using a scanner and it's very hard for Teemo to punish people for trying to remove them without putting himself in danger.
That leads into my problems with his abilities - None of Teemo's abilities are particularly satisfying to land, nor are they satisfying to play against. Teemo's Q is only good against champions who auto-attack, and in those cases it's absolutely crippling- landing a Q on a marksman or other auto-dependent champion will completely hobble their ability to fight no matter what they do (which isn't that fun for them), and against literally anyone else it's basically just a point and click damage ability. I think, if Teemo's blind worked more like Quinn's then it would have a much bigger impact- Melee champions wouldn't be so infuriated and they'd be rewarded for finally closing in on him because his trick doesn't work at close range, and he'd have a bigger trick to used against ranged champions that prevent them from trading easily with him.
His W used to make him a slippery bastard, but in a meta that has so much mobility, it really, really isn't enough to keep Teemo away from anyone. The passive movespeed is fine, but if I was trying to redesign Teemo, I'd replace the active with a dodge-roll, a little like Vayne's. I'd also make it interact with his passive, instantly cloaking him if he dives into a bush so he can use his passive again.
His E is a passive ability. It's emblematic of Teemo to have poison damage on his auto-attacks, but I feel like if Riot made Teemo as a brand-new champion today, they'd just roll in the passive poison damage with his actual passive, or make E an active ability with scaling passive poison damage on the side, or make the passive poison damage scale with his Q. It doesn't provide any interesting outplay potential on either side, except maybe using a shield to mitigate some of the damage-over-time. This space could be used for a completely different ability-- maybe a damage steroid for his poison that has to be channeled like Edge of Night, and can only be used while he's in stealth. Maybe it could be some form of sustain to put him on equal footing with battlemage champs like Swain or Vladimir. Maybe it could be a huge burst of damage against poisoned targets like Cassiopeia's E or Twitch's E. I'm not sure, personally.
His R is The Shrooms. Really, this is what Teemo is famous for, and what makes him so annoying. As a Mastery 7 Teemo, I assure you - I don't like the shrooms either! Teemo's shrooms are pretty much emblematic of his "capitalize on enemy mistakes" problem, because shrooms only ever deal damage if the enemy makes the mistake of stepping on them. The only way you can really be clever with this is by throwing them in the middle of a minion wave, where it'll go off the moment it primes, but this gives your opponent a big honking 1.5 second window to not be next to their minions (1 second for the shroom to prime, plus the time it takes to get there) so even that isn't much of a trick. I mean, there's also the mushroom-bouncing trick, but come on, who even uses that? And even when the shrooms are stepped on, they don't a whole lot of damage - Which is a good thing, don't get me wrong! If a squishy stepped on a shroom and was oneshot by it, that'd be infuriating - but even at max level with 400 AP, the shrooms deal 650 premitigation damage (not counting effects like Liandry's Torment or Luden's Echo), so it can be counted on to half-health a squishy, maybe - but it'll take 4 seconds to do it, and oh look Caitlin just got all her health back with bloodthirster because it's lategame. In a teamfight, Teemo would probably have to land two shrooms on the entire enemy team, spaced four seconds apart, to have the same impact on the team as someone else would in his place - and like I just said, that's easier said than done.
Instead, I think it would be more interesting if Teemo's shrooms were more like Gangplank's barrels. I would have them remain invisible like they are now, with a 1-second window to see where he's put them, but instead of going off when someone steps on them, Teemo sets them off remotely like a remote-detonation charge by pressing R on them again (possibly with a split-second area indicator warning the opponent of the impending explosion and possibly letting them flash or dash away). I would also remove the vision they grant. This remote-detonation needs to be within a certain range (what I figured was acceptable would be the distance from the middle of toplane to the first turret), and Teemo would have a short animation of taking out the detonator or whathaveyou to set off the shroom. They would still be revealed by Control Wards and Scanners, but going to remove them is now a risk, because if Teemo is within range and sees you trying to kill his shroom, he can potentially set it off in your face instead. This would encourage Teemo to heavily fortify a nearby area or place mushrooms on important objectives in order to try and steal them (or try and kill people who are trying to take them), instead of littering them all over the place- And this change also handily means that if Teemo sets off a shroom, that tells the unfortunate victim that he's close and that he's watching. And, on top of all that, if the shrooms need to be activated by Teemo himself, they're also allowed to do more damage! I think this would give Teemo a better ability to play mindgames with people as well as a bigger teamfight impact, especially if he traps an objective heavily and catches out the enemy team trying to take it, while at the same time giving the enemy more information to counterplay his shrooms in a way other than just "buy a sweeper".
In summary, as someone who loves him dearly, Teemo's in need of a rework. Maybe not as badly as Nunu or Malphite, but nonetheless, as more and more champions come out, Teemo's kit starts to show its age as he finds himself more and more without a place in the meta. Maybe a lot of players would just wish he would go away and never come back, but I think Teemo has a really cool gameplay concept that can be delivered on in a way that's interesting for both Teemo and the enemy team to deal with - after all, they managed to make Evelynn more interesting to play against, so why not? Teemo could even be completely reworked to leave toplane entirely and become a viable jungler who focuses on counter-jungling and area control (maybe using that free space with his E!). It sure would make Omega Squad Teemo's quotes about the jungle make more sense.
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