As someone who plays mostly solo-queue games, I have to rely on myself to be able to fill as many roles as possible on my team with a single champion. I've recently found that Annie seems to be the perfect champion for the job.
Roles Annie Can Fill:
AP Carry - She's got 3 powerful attack spells, much like Veigar, Anivia, Fiddle...
Initiator - Tibbers with a full stack of Pyromania = 5 people stunned and hurting.
Pusher - After dropping Tibbers, his attack and damage aura combined with Incinerate clears creep waves in seconds. His melee is great against towers.
Tank - Molten Shield is basically Defensive Ball Curl with a different animation. Combine that with HP items, plenty of stuns, and peoples' tendency to target casters and you have a winner.
Crowd Control - With a bit of CDR, you can stun like there's no tomorrow. Time it right and you can disable multiple enemies once every 8-10 seconds.
"So what if she can do everything? Building a balanced team allows you to do all that and better."
This is true, however the reason she shines so much is because you don't know what you'll be up against until AFTER champ select. Annie is amazing because she can easily adapt DURING the game depending on the opposing team - and her skills are guaranteed to synergize with a variety of item builds.
Personally, I like to emphasize Annie's flexibility in my rune/mastery setup, and even run a mix of quints.
Red- Magic Pen (Insight) - This is a no-brainer
Yellow- Dodge (Evasion) - This is a matter of personal preference; I'll explain below. Health or MR could also work if that's more your style.
Blue- AP/Level (Force) - "WHAT?! NO CDR?!" Yeah yeah, I know. But here's the thing: Settling into your role will require items. If you want to farm quickly, you're going to use Incinerate. This leads to running out of mana pretty fast, and Force runes make you better at blowing up ranged minions or Wraith/wolf camps. It's easier to itemize for CDR imo.
Quint- Personally I have 1 Insight(Mpen), 1 Fortitude(Health), and 1 Potency(AP). Play around and see what you like.
I've played with a lot of different mastery combos, and I've really started to align with the argument that deep Offense just doesn't do a lot for caster heroes. Defensive talents benefit you all the way down and, even if you're filling the AP carry role, you'll be able to capitalize on Annie's survivability.
3/3 Archmage's Savvy
1/1 Archaic Knowledge
3/3 Strength of Spirit (Amazing HP regen)
4/4 Evasion + 1/1 Nimbleness (NOTE: This is ONLY worthwhile if you got dodge runes. If you don't have a decent amount of dodge, just max Hardiness and Harden Skin)
4/4 Veteran's Scars
I almost always get Flash and Exhaust.
Flash is great primarily because it helps you initiate. The enemy team will distance themselves from the brush, and Flash + Tibbers' great range will allow you to get the jump on your victims even if they're playing cautiously. I'd almost consider it mandatory.
Exhaust is useful either to shut down a physical carry in a teamfight, or slow a gank target long enough to build up another stun.
Other Spells you could use in place of Exhaust: Teleport(Clutch for porting to another lane and shutting down a gank attempt, or just staying competitive in a tough lane), Ignite(Don't you hate when they get away with like 100 hp?), Clarity(Because you can never have enough mana)
A lot of people like to start with Incinerate and charge up a stun. I would NEVER do this unless my team was planning a level 1 gank. You need to capitalize on your farming power ASAP.
4: E(Molten Shield - one rank of this is good for Pyromania stacking)
6: R(Summon Tibbers aka First Blood)
7: W(As pointed out in other guides, Incinerate gives more dmg/level from this point on)
Your core build is Catalyst and Basic Boots. You should start with a Sapphire Crystal and Health Potion, and have enough gold(1275) for both core items on your first trip back.
From there, a whole world of variation is possible depending on what you're up against.
A full-on AP carry build would probably be RoA, Sorc Boots, and Mejais, then-
Deathfire Grasp (if they have a tank) or Rylai's(if they don't) or Void Staff(if they're rushing Banshees)
Guardian Angel(if they're physical heavy) or Banshees(If they're magic heavy). Both great for preserving Mejai's stacks.
This can be augmented to varying degrees of tankishness by getting Banshee and/or GA earlier on, or maybe even a Frozen Heart if they're REALLY heavy on characters like Tristana and Twitch. You'll usually want a Mejai no matter what, but if you end up doing most of the "tanking" then your K:D won't be as hot and your gold will be better used elsewhere.
A Special Note on CDR-
You've probably noticed that there's little to no CDR in the items I've listed above for Annie. It's an amazing stat for her, but IMO it's just not worth rushing it. Earlier teamfights will regularly see you going OOM plenty fast, and later teamfights make it easy to go in with a Brilliance elixir and at least one CDR item or Golem Buff or 20 stack Mejais. Late-game you should definitely endeavour to be pushing the cap on this since your stuns will be more meaningful than your burst damage.
If you can get solo mid, do it. Tell Ashe to die in a fire. Your early-game burst is lethal if you can get ahead on levels and mid is the best place to capitalize on this (both in terms of leveling up, and easy access to side lanes for ganks).
Levels 1 through 6-
Your focus here is to acquire as much gold as possible. Last hit like a boss with Disintegrate and don't even bother shooting spells at your opponent unless you have a full stack of Pyromania. Even then, you don't want to be missing lasthits because you're trying to stun them. If you really insist on harrassing, use your auto-attack to do it since it has exceptional range and won't slow down your farming.
If you paid attention during the load screen, you should know what summoner spells their solo has and whether or not you can pull off a flash/tibbers/nuke/nuke first blood. Do it if you can, since this will create an ideal shopping opportunity and it's best to have your Catalyst and Boots before you try to gank anything.
Levels 7 through 13-
Once you have your core items, your focus will shift a bit from farming to ganking. This is the perfect time to take pressure off the side lanes and push a tower or two with Tibbers. Flash and a full stack of Pyro will give you easy kills, or at the very least force the enemy to play cautiously. Keep in mind that your burst is VERY high compared to their survivability at this stage of the game so don't be afraid to tower-dive for an easy kill. Their souls shall feed your Mejai.
Levels 14 through 18-
A few very important things will begin to happen by this point.
#1: If you've done your job right, the other team is probably focusing heavily on trying to kill you. At the very least, they're roaming around 4-5 at a time so as not to be caught alone with you.
#2: If the other team has any sense at all, their MR should be increasing at this stage. More often than not they'll all just buy banshees and assume that they're safe. So what? You can go in with 4 stacks instead of 5, Incinerate their shields, and LOLTIBBERS them anyway.
#3: You should be running around with a good chunk of AP and level 5 incinerate, even if you're built tanky. This let's you clear out minion camps or waves of ranged minis with amazing speed. Annie can farm almost as well as Singed by this point, and that plus the gold from all your hero kills earlier on will mean that you have not only a level advantage, but also a very significant item advantage as well. Take this time to "dress for success" by grabbing a banshees if they're using a lot of nukes or disables or get a DFG for their beefy tank, or just lots more AP if you're snowballing them, etc...
And ultimately that's what it's all about. You want to build on your advantage early and convince them to surrender before you ever see the late game. If for some reason they enjoy being torched by you and try to make it last...
Level 18+ and onward-
If the game drags out to the point where everyone's level 18 and has a good chunk of MR, your capacity to blow people up will be pretty seriously diminished. But if your team has any sense you should still be able to dominate the game by focusing more heavily on your position as the Supreme Purveyor of AoE Disables. This is the point where you really want to go for CDR if you aren't already capped.
Should the opposing team be incredibly stupid and not choose to pile on MR, then just walk into their base, show them Tibbers' business end, and spam /taunt and /joke while your team takes out their Nexus.
Tips and Tricks:
1. Molten Shield offers a noticeable boost in survivability even at level 1, and costs barely any mana. It's also effective when killing neutrals. Use and abuse it!
2. Your ability to stun enemies is good not only for attacking, but also for getting out of bad situations. You may not be able to heal teammates, but you can definitely prevent their deaths with a well-placed disable. Building your pyro counter while fleeing can also turn a losing battle into a double kill.
3. Tibbers isn't on a very long cooldown, so don't worry about saving him for a team fight unless it's late in the game. You can rack up an alarming number of kills by being super-aggressive when you have Tibbers in your pocket.
This is the first time I've tried writing a guide, so hopefully people find it helpful. Feel free to give feedback as well, and good luck! =)
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