I thought I'd write a little(overly comprehensive) guide on my favorite and most played hero, Corki the Daring Bombardier. I've got over 550 corki games under my belt now (handle h3w0), and have tried just about every build/rune/mastery combination under the sun, and I swear to any/all deity's that if I see another trinity force build I'm going to cry. If anybody wants to see the build in action feel free to add me up and play a game. I used to play a lot of competitve dota (over 4 years) and my favorite hero for a long time was Puck, who I believe corki is the closest LOL counterpart to. Blink and spell domination? yes please.
As a preface, I'm not completely hating on atk dps corki. It works alright I guess, but it doesn't feel nearly as competitive or aggressive as pure AP. AP plays VERY differently from atk corki. As far as play styles go, ATK corki is a farmer/late game carry, and AP corki is an unstoppable engine of gank, rocketing his foes with impunity. So here is the build to shock and awe your opponents with lethal salvos. Between the many times I've played both builds though, AP always ends up carrying a lot better than ATK. If you want to do insane damage from 1000range while having a tanks hp, this build is for you.
This guide is intended for solo mid corki, and I haven't tried this build at all in the lane with somebody else. Corki flies solo, get it?
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Viable Summoner Spells
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1. Flash: Flash used to be mandatory, but after having minutes tacked onto the cd and the range chopped, its a little more preferential now.
2. Teleport: I always take tp as my second, for a few reasons. First off, if you are solo, it is necessary to keep your exp/farm up early on. Most importantly in the first 10 minutes, you'll use it for a free mana refill/buy with no time out of the lane. After that, it becomes a great asset in teleport ganking other people. Just wait for a figth to start then tp on the most oppurtune creep. Most people tend to get tunnel vision when they go after kills and dont see the tp swirls, assuring you kills.
3. Cleanse: The flash, she aint what she used to be. I don't take cleanse on corki, but there isn't anything wrong with it.
An added note on tp, VERY few people abuse tp'ing to wards/mushrooms/jack in boxes etc. Dropping well placed wards in their jungle/sneaky places will net you some ninja tp kills.
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Mastery
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9/0/21 is the only way to go. I don't see much of an argument for anything else.
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Runes
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My personal rune build is a little eclectic, but I feel it works.
Reds: Magic penetration all the way. Given corkis ap ratios, you will get much more bang for your buck out of penetration.
Yellows: Hp@18
Blues: +11mana (base). These are really underrated. People favor the mpregen@18 blues, but you will be getting much more out of these for your first 6 or 7 levels. Corki is all about dumping a bunch of spells at once, not a few over a long period of time.
Quints: I roll with 2 +32hp and 1 +2magic pen quints. 3 hp can be ok as well.
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Spells
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Before explaining, here is how you level them.
1.Phos Bomb
2. Valk
3. Phos Bomb
4. Gatling
5. Phos Bomb
6. Rocket.
7. Phos Bomb
8. Gatling
etc
Phosphorous Bomb: [CD 8 second//90 base mana cost with +10mana cost per level]
It has a targetable range of 600, and an aoe of what I believe is 325. This is your main damage source early on. Dealing 80/130/180/230/280 damage, as well as having a 35pct mis debuff and reveal stealth benefit. This spell has so much utility it makes shaco bluff. It has a .5ap modifier.
Valkyrie: [CD 20seconds//100 mana cost]
While it isn't as far as it used to be (only 700 max range now) it is still amazing for leaping walls and terrain, or just putting distance between yourself and others. Most people only use valk for escaping, but it can be used very well offensively, as it does deceptively high damage over time. You will die countless times however after using valkyrie to try and kill someone only to not have it for your escape, so play it safe and smart. It does 60/90/120/150/180 damage per second with a .4ap modifier. It will still be your lowest dps source throughout the game regardless of its potential, and is mostly used for its leap mechanism.
Gatling: [CD 16 second//60 base mana cost with +15 cost per level]
As AP corki this wont do too much damage. It is still very nice for its armor reduction though, as that will greatly help your teammates. Spraying this all over the other team is a top priority to help your teams dps, as well as your own. It is also the extra boost you need to kill somebody alone many times. Once you get rylais, gatling gun should be renamed to 'Death Trap', because a persistant slow/armor reduction is savage. It lasts 3/3.5/4/4.5/5 seconds, reducing 1 pt or armor per level per second. It has 600 range, in a frontal cone.
Rockets: [No CD but limited ammo/25 mana cost +5 cost per level]
You get one rocket every 14 seconds, to a maximum of 7. Every 4th rocket is a double damage world ending patriot missile. They deal 125/200/275 damage. Rockets are the main stay of AP corki. While many scoff at their measly .3ap benefit ratio, the real beauty is that you can potentially unload 5-6 on someone within just a few seconds. They can be very difficult to aim with their miniscule hitbox. The trick is, just stay calm. Many people freak out (especially on seeing a low hp enemy) and unload all their rockets in a hectic frenzy trying to hit somebody. You are VERY crippled when out of rocket ammo. You need to conserve ammo, and pick your shots. Don't panic and click everywhere, stay calm, focused, look about .5seconds-1second ahead of them, and aim. When alone (in jungle or river or without creeps in lane) they can be very hard to hit someone with from afar if they are consciously trying to dodge it. It really isn't too hard o dodge and weave. The real beauty is the range though, as well as shooting over terrain. It is usually good to aim with the blast radius in mind, aiming to hit a creep close to somebody instead of trying to hit the moving player. Rocket aiming tends to make or break AP corki. When you first hit 6 its usually good to save up at least 3-4 rockets before using them, so you can create some burst at least. A lot of your kills later on will be from finishing people off with 2-3 rocket shots. Generally, if you only have 1 or 2 rockets, don't even fire them unless its a desperate situation. Your burst is heavily reliant upon your rocket management.
Passive: Hex-Tech Shells
Your base attack does an additional 10pct true damage. Very nice for harassing early on. Many people use this and gatling as the justification of ATK corki, but 1 atk ability and 1 atk passive vs 3 spammable ap spells seems like an obvious choice to me.
I don't max valk till last. It can be nice to max earlier for its damage, but most of the time it will be used for escaping, and valking over a group of ppl is a death sentence without flash to get you out afterward.
If you feel that you are a candidate for getting level 1 ganked, take valk first just so you will be safe. If you have valk and flash at level 1 you pretty much have to let them kill you.
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Items (updated)
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Go out the gate with a Sapphire Gem (400g) and 2 health potions (35gx2)
1.Your first item and main priority is turning that sapphire into a catalyst. The catalyst will keep you in the lane, and give you a very nice buffer of hp. It costs 925g to create catalyst from the sapphire. I almost always return to get the catalyst as soon as its viable. If you have tp up, a base buy and tp back out with catalyst is preferred. You want to get this thing on you as early as possible.
2. Boots (350g) which you will turn into sorc boots(another 750g). Gotta love that magic penetration. If your lane is going very well early on, it can be worth waiting to have ~1275g to buy catalyst and boots, since the added maneuverability is very helpful, especially against most other solo champs who seem to have ability's that require dodging.
3. Time for some decisions. If you are feeling good about how you/your team will score, then hit up Mejais. If you don't think snowball items are wise in your game, going straight to Rylais can be a good option. If you end up buying mejais, you should immediately start building a Rylais starting with giants belt right afterwards.
4. With your Rylais and optional soulstealer, turning that catalyst into a Banshee's Veil is probably a good idea. You are most likely going to be taking some focus in teamfights, and even with tons of hp and a spell shield things can get dicey.
5. Check out the opposition. Not as much magic resist as they should? Zhonya's. Some magic resist? Void Staff. OUR TEAM IS 5 AP AND THEY ALL BOUGHT MAGIC RESIST! Get a lichbane to convert some of your damage to physical.
6. Every item worth getting on an Ap build has already been mentioned. While Ap corki needs boots catalyst and rylais, the other slots are situational and should be tailored to the opposition to maximize damage.
Every game is different, and sometimes you may have to change your build some for your opponents. Generally speaking, in an average game, you should have catalyst/sorc boots/soulstealer around 15-18 minutes. Finishing rylais somewhere aroudn 25 minutes is very powerful. If you pull out the rylais pre or @ 20 mins, they probably already plan on surrendering in 5minutes.
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The Early Lane
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Corki used to be a MUCH better solo mid than he is now. He hasn't been nerfed, riots just been pumping out a lot of OP lately. While you can be fairly aggressive around an ashe or sivir, good nids or kats can make for a "fun" game.
Here are some nice rules to abide by early on, and they are prioritized from 1 downward.
1. Dont Die. This is your main priority always in LOL. Very few instances is something worth dying for. Especially with you as the carry and a soulstealer, not dying is your main focus.
2. Don't let your opponent outfarm you. Hit tab to check creep scores often. I'm of the opinion that its unacceptable for just about any hero to outcreep corki in the lane (except maybe turret heimer). If they have more creep kills, you need to turn up the juice and make them fear coming in close. Time your harasses to when they would be last hitting one of your creeps.
3. Farm. Get those last hits. Don't auto attack it over pushes your lane and makes you look bad (because you probably are bad).
4. Try and kill them. It may seem silly to put killing your opponent at the bottom of the list, but if you are dying/getting out farmed in the process of trying to put hurt on them, its not worth it. If you aren't able to secure a kill, all you are doing is wasting time and mana while they outcreep you. If you are against a very solid player they probably wont die to you 1v1(nobody should die 1v1), so just outfarm them.
Corki has one of the best last hits in the game, and can easily get most every creep in a wave if you just time it instead of auto attacking. Don't auto attack creeps early on by the way, it makes you look bad.
As far as fighting against your lane opponent, there is a general rule for 1v1 engagements. They won't die unless they give you the kill. That's not to say most people wont be willing to let you kill them. Being killable usually means they are being offensive and trying to hurt you, but that's the main way people expose themselves early on. If you can tell your lane opponent is a very cautious player who is just there to creep, dont be overly aggressive and let yourself get hurt needlessly trying to harass them. If they want to creep, then fine, because few champs can out creep corki. Just make it your commitment to pepper them away from the wave and outcreep them.
Pre-level 3 you are very weak. I only use 2, maybe 3 phospho bombs before level 3, cause it doesn't hurt too bad at rank one and you want to save your mana for higher ranks. Don't not use it at all though, that wastes mana regen and the extra mana you get on level ups. When you wait to spam until level 3 or 5, it can also make your opponent think you are a more passive player than you really are, making your damage explosion all the more surprising.
Once you hit 3 its time to turn the heat up with your newly painful phospho bomb. As a rule, save your valk for escaping (never know when someone is waiting to see you use your escape so they can come out of bush) and only use gatling gun when its going to be a kill. Otherwise, your mana is only for phospho bomb. It has decent range and is fairly easy to target.
One of the main ways you will get an early kill against your lane opponent is Flash-> phos bomb very quickly together. If you have someone low but they don't want to return yet, they will try to dance outside of phospho bomb range and soak up exp. If you are quick, even an opponent who has flash themselves probably wont have time to pull it off, since phosphorous bomb is instant. It is even fairly easy to tower dive at level 4-5 for a kill with flash in and valk out. Always save the valk for the exit, since it is much slower and they have more time to react if they see you valking in instead of a flash.
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Somewhere around 15 minutes
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WHY AREN'T YOU GANKING PEOPLE YET. With two blink mechanisms and tons of firepower, everybody but pure tanks will be crumbling to your solo items/exp, unless they got fed by noob teammates. I'm a big fan of wards. Placing a few in river (by dragon etc) will save you and create many gank opportunity's. The longer the game goes on the more it becomes a team effort, but by solo'ing mid you've committed yourself to carrying your team. You need to be the impetus behind most of your teams ganks. As soon as I get my rank1 boots on though, I try to be all over the map. Watch the minimap religiously. When you see someone with gankable hp, head there as sneakily, but quickly as possible. Don't let your lane opponent see you walking top, they will probably give their buds a heads up. Wait until you are out of sight of creeps/champs.
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Tough Opponents to Lane Against
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Heimerdinger: Kinda obvious, but he is the easiest solo hero in the game. He only dies if he wants to get close enough to be hit by you, which a good heimer wont. Against heimer, you just need to be committed to keep up with his farm. Once you get rockets, save up a small barrage of 3-4 so you can phos bomb and rocket a cluster of turrets down quickly if he is getting too set up in the lane. Give him nothing. Take from him everything. EDIT: his rocket range has been nerfed since I wrote this, but he is still a pretty strong solo. He just maybe might have to get sort of close to you to rocket now.
Katarina: Kat is back. About 4-5 months ago she was one of the best solos and got hit with the nerf bat, but she is back with a mean vengeance. The only saving grace against kat lanes are they are 100pct predictable. You should know the range on shunpo and bb, and their summoner spells, and manage your hp accordingly. On the plus side, lots of bad people play Kat since they think shes an easy win, so you might have that going for you.
Fiddlesticks: 1v1 Fiddles will hard counter corki. You shold focus solely on last hitting and farming. No amount of damage you do will negate his heal from drain, and with no cc there is nothing you can do to stop him. Play safe with your hp and farm.
Nidalee: Oh hey its that hero riot refuses to acknowledge is op and wont nerf down to reality. Hope you like heal and auto attack. Bring a pillow, because this lane is a snoozer. Last hits galore, with no fighting (cause you stand no chance of killing nid early lane unless the player is a noob)
Tristana: Trist starts off very strong agaisnt corki, but somewhere around level 4-5 corkis firepower becomes too much for her. You must play safe the first few levels, and get ready to turn up the heat as you hit 5. Trist stands a decent chance of killing corki 1v1 under level 4, so watch your distance.
Pantheon: He's nothing a very aware corki can't handle, but all it can take is a single slip up and you can be absolutely melted by his HSS. Be mindful of his range, and dont be afraid to go back to base early and get some boots so you can play the range game against him better.
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I can't really think of anything else to add at this point, which means I guess I'm done. If anybody has any more questions I'll answer them the best I can. Feel free to add me for a game if you want to see the build in action. Thanks for the read, and remember, stop the unwarranted hate on AP corki!
Edit: Changed a few things to reflect some of the patches that have come out. Guide is current again.
editedit: More months, more patches, more updates. Most attention given to items and laning tips
edittt: cleaned up runes and masteries section. changed laning tips.