Janna is the beginner hero, easy to get into since her abilities are very similar to a standard mage from most other MOBAs. Immobile, squishy, but tons of AOE, burst and CC. And a little DPS too. All of it from range. She's a good beginner champ to start learning the DPS role with (named Assassins here), since her passive allows her to kite easily; considering kiting is the basic skill for most ranged DPS champs, she is a solid pick to ease your learning curve. You can compare her to LOL's Ashe, although of course she is a mage with CC and burst, unlike Ashe who's pure DPS.

Pros:

+ Permaslows.
+ Good AOE.
+ Good AOE CC with (Cold Snap) Ring of Frost and Numbing Blast Cone of Cold.
+ Decent DPS with (Icelance) Frostbolts and (Wintermute) Water Elementals.
+ Great waveclear and pushing power.
+ Defensive and outplay capabilities with innate Improved Ice Block (equivalent to LOL's Zhonya) and some talents (Frost Armor, Ice Blink, Ice Barrier).

Cons:

+ Squishy.
+ Immobile.
+ All abilities are skillshots, thus easily juked.
+ Needs a frontline to maintain DPS, thus poor objective control.
+ Scales, weaker early.
+ Ultimate dependant.

Strong Against: Melee without gap closers, Squishies without mobility or jukes, clumped up teams.
Weak Against: Assassins of all variety (and by Assassins I mean melee burst with mobility/stealth).

(A) Sorcerer Build - AOE/Burst

Cores - Ring Of Frost, Cold Snap
Secondary - Ice Floes, Northen Exposure, Arcane Intellect
Tertiary - Fingers of Frost, Storm Front

(1) Fingers Of Frost (*) - If you can collect 20 globes, you add 10% to your burst. Not bad, mainly because there aren't many talents for AOE/DPS in this tier.

Winter's Reach (*) - Helpful if you feel the game will end fast, and you're taking Arcane Intellect anyway. Idea behind it is that you'll ideally burst enemies at a long range so this will help you snipe better, alongside Storm Front.

(4) Arcane Intellect (**) - Pretty important, since the point of this build is to push like crazy and roam to catch people out with your burst. Helps a lot to not run out of mana even if you waveclear with both W+E.

(7) Ice Floes (**) - Extra AOE right now mostly helps in waveclear and helps in not getting it juked; but that and the CDR is godly in large teamfights, which is where you shine.

Ice Lance (*) - Little more single target DPS. You can actually get off 2-3 Qs in one rotation (if you hit your R) with this, so it counts as burst, albeit only barely.

(10) Ring Of Frost (***) - No contest here. Just make sure you land a basic ability first (or chain it on another ally's CC) to prevent an enemy from just walking out of it.

(13) Storm Front (*) - Good long range engage. W into R into Q into E does massive damage. If you're taking Northern Exposure, it still remains useful to slow enemies with a long range W into E>Ult>Q. If you've played Jaina, you'd know how annoying short her blizzard range is, and for a squishy burst mage with no defensive abilites, it is a bit too short for my liking. Hell, its actually slightly shorter than cone of cold, which is supposed to be your short range ability. More for convenience.

Icy Veins (*) - If you're a perfectionist, you'd want this for maximal burst over Storm Front. Sure, now you can't burst from gigantic range, but your DPS up close goes up a lot for 5 secs (still counts as burst, somewhat) because with Ice Floes/Ice Lance you can easily spam your E/Q multiple times in one rotation.

(16) Northern Exposure (**) - Helps a lot in teamfights alongside Ice Floes, which is where this build should shine. Helps your burst too, but not as often as you think because of the short range of E making it unlikely you'll start off your combo with it.

Numbing Blast (*) - Isn't exactly ideal since your R delay is 1.5s while this is 1s duration root, but if you R first on an unsuspecting opponent (or during Chaotic teamfights) then E then its a guaranteed Ult (double Ult after 20 if you can catch them at the centre) for a big nuke. Not as bursty, but more reliable.

Snowstorm (*) - Since we're talking AOEs, why not take the most AOE'est ability here? The main reason is that with Ice Floes and Northen Exposure and Ult you already have good AOE, you don't really need better; but still, since its AOE; it doesn't hurt to have in teamfights.

(20) Cold Snap (***) - No competetion. No other abilities on this tier provide burst or AOE to this scale. Yeah its not guaranteed, but thats what your teammates CC's are there for.

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