[1.3]Fireball Witch guide for beginners

You can either have a life based build or take Chaos Innoculation. I recommend a life build though: Fireball has a relativ high mana cost (higher than freezing pulse for example). CI users might run into mana problems without additional mana/manareg on gear as they can't take Eldritch Battery like life based builds.
Even if you plan for CI it is recommended to start as a life char. Why? It is much easier to get life on gear and to have a big life + ES pool than to level with only a much smaller ES-only pool. You will get passive respec points along the way that you can use to spec out of the life nodes later.
The usual progression is: You go life until you reach act 2 merciless (you should be in your late 50s lvl by then); some even delay going CI until they defeated merciless Vaal. At the beginning of act2 merciless you will have 14 passive skill refund points you can use to spec out of life. By then you should have collected ES gear that will get you 2000+ ES (another reason CI is a bit tricky if it is your first char).


Your first steps should be to get life nodes and lay the basic path for the final build :


After that life and CI trees start to develop in different directions:

The following setups is for 5 links. If you only have a 4 link i would skip fire penetration although that also depends on what gems you already have: Fire penetration is a quest reward in act3 normal (severe the right hand) whereas conc.effect is a very late reward in act3 merciless in the archives (and i would rather pick Spell echo or Cast when Damage Taken in that quest). So you might end up taking fire penetration over conc. effect in the setup because of this.

Fireball – Lesser Multiple Projectiles – concentrated effect – life leech – spell echo - (fire penetration)

Fireball has the big advantage that it can shotgun enemies (unlike bow attacks or ethereal knives). That means all three projectiles can hit and damage a single target for multiple damage. I recommend LMP over GMP for two reasons: First LMP is available early on (weaver quest in a2 normal); second it has a lower mana multiplier. If you have access to GMP later in the game feel free to replace LMP with GMP and see if your mana can support it. Shotunning bosses with five projectiles instead of three results in higher damage (though the burn damage will be a bit lower).
Concentrated effect is probably the biggest damage boost fireball can get. The explosion radius of fireball is pretty meager to begin with so you won’t lose much by the conc.effect penalty. LMP is enough to cover crowds. Be sure not to use pierce/fork/chain with conc.effect as it will have no effect on piecing/forking/chaining projectiles. Only the last enemy that is hit without further piercing/forking/chaining will be hit for More damage.
Spell echo Introduced with 1.1.5. and a must have in the setup imho. Free additional cast! Once you have it (Library quest a3 merciless) replace fire penetration with it.
Fire penetration lowers the resistance of the enemy. You get a flat damage increase no matter how high its initial fire resistance. For mobs with 0% resistances that means 30+% more damage. When looking at max resist mobs, lowering the resistance from 75% to 45% will give 120% more damage, making it the best support against high resist enemies. Don’t be fooled by the tooltip dps not changing. You get more damage by lowering the defense not by upping your offense (though the final result is the same)


Secondary attack:
Fire Trap – concentrated effect – fire penetration – increased area of effect or multitrap
Iaoe to counter the radius penalty of conc. effect. Or use multitrap and lay 3 traps at once. Find out by yourself what fits your playstyle best.
Why fire traps? Two reasons:
- If you encounter elemental reflect mobs you can switch to fire traps as they don’t reflect the damage back to you.
- Its burning ground effect stacks with the burning caused by ignition:


The actual playstyle would be to use BOTH fireball and fire trap, instead of waiting for some special occasion (reflect) to use fire traps. Not only does the burning stack, but fire trap compensates very well for the suboptimal crowd control of fireball: When facing a large crowd the LMP projectiles will hit the first row of the mob but will not effect the ones behind because the fireballs won't pierce and have a restricted AoE (-> conc. effect penalty). Throwing fire traps gives a very nice AoE damage in those cases.

Now there are a lot of variations on gem selection and playstyle:
You may want to use firestorm as main spell. Unfortunately I never used it so I can’t comment on its usefulness. Sorry.
Another setup would be to build around the burning effect. In that case you would drop concentrated effect in favour of elemental proliferation; maybe replace LMP with chance to ignite. Hit one and let the burning spread and finish the mob off. For obvious reasons that mechanic is not efficient against single targets like map bosses. This being a beginners guide I therefore recommend the more one-spell-fits-all approach with LMP and concentrated effect.
Same goes for the use of faster casting (as gem and as passives in the tree). FC gives a nice damage boost but has a hidden downside: it also increases your mana needs as you will cast more spells per second. You have to be very careful with too much cast speed on a fireball build, as FB consumes a lot of mana per cast. Even with eldritch battery you can easily screw up your mana pool with too much cast speed. A word of warning: don’t get fooled by tooltip dps. FC increases it, fire penetration won’t, though if you replace on gem with the other your REAL damage won’t differ that much (if at all).
Power charge on critical. When starting a char you don't want to use that one. The reason is that PCoC gives you a CHANCE of aquiring power charges (that would increase your critical strike chance) in case you crit with your spell. The problem is that in the beginning your base crit chance on your spell will be very low, meaning PCoC rarely ever triggers.
PCoC is something you want to start using when your char has reached its finishing stages and you start tweaking around to optimize your dps and gear. Picking up power charge nodes in the tree, thinking about a 6L chest, void battery unique and other advanced stuff comes into play then.

Vaal Gems
Vaal Discipline is a very good defensive option for CI builds as the ES recharge is not delayed by damage taken for several seconds. Nice oh shit button for tight situations.
Vaal Molten Shell : Unlike normal Molten Shell it doesn't need a certain amount of damage to trigger, but does so on EVERY hit you take during its duration. Linked with concentrated effect - increased duration (and life leech if on a 4 link) it is the best offense-defense combo in the game imho. Instead of being overwhelmed by large numbers all that is left is ashes after you are being hit 3-4 times. Might be worthwhile to use it instead of CWDT (sadly there ain't enough sockets to use it all). Best used with a life build that has armour and can take 2-3 hits without kicking the bucket.

Auras:
All auras should be linked to a reduced mana support gem. A full leveled red.mana will decrease the reserved mana to 71%. An aura that normally would reserve 60% of the mana would therefore only reduce 43% (it will get rounded up). There are several nodes in the tree that could further reduce those costs like Sovereignity. BTW additional quality on a reduced mana gem will NOT further reduce the amount of reserved mana when using auras but will only lower the mana costs of skills used (for example lower the cost of casting fireball if linked to it).
For a life based char only 2 auras are mandatory:
Purity of elements which will increase elemental resistance (its 40% reservation will get down to 29% with a lvl 20 reduced mana)
Clarity which will increase mana regeneration. It starts with 64 mana reserved and goes up to 520 mana reserved on lvl 20. So be careful when leveling that gem. Make sure the rest of your mana is enough to spam your main spell. Anyway with only two auras running one should be ok even with a high leveled clarity.
For a CI things get a bit more complicated. Not only will one need Clarity and Purity, but also
Discipline which gives additional ES.
Discipline is a 60% aura (43% with red.mana). That’s 72 % reserved mana without clarity. Things might get a bit tight here. That’s the reason for taking reduced mana nodes from the tree for another 8%-20% reduced mana. With a lvl 20 reduced mana that leaves enough room for clarity (though probably not fully leveled; be careful here) and enough mana to spam the main spell.

BTW if you can get a Purity of fire/purity of lightning try leveling it up in the second weapon slot. There are situations where it is beneficial to swap purity of elements for one element (Fire for crematorium or General Gravicius; lightning for barracks, crematorium piety or map piety for example)

Heralds:
Herald of Ice
Gives additional cold damage to your spells but reserves 25% of your mana. If you can sustain it, use it! Don’t if you have to drop a purity instead and no longer have max resists. Remember: dead witches don’t do damage.
Herald of Thunder
Works really nice with crit builds as the added lightning damage is enough to shock normal mobs on crit constantly triggering the lightning storm. It really shines when linked to curse on hit and a curse. With a high crit rate the mobs are constantly hit by lightning and therby cursed. Makes for a smooth gameplay as you don't have to pause for manual cursing.

Curses:
Use flammability for offense and temporal chains (or enfeeble) for defense.
When playing in a party cursing elemental weakness instead of Flammability might be more beneficial as most of the times other players will be dealing some other elemental damage.
Assassin’s Mark
When reaching lvl70+ you could replace flammability with Assassin’s Mark (formely known as Critical Weakness): With high enough crit chance you do more damage with it if you have roughly an extra 100% increased critical damage with gear/support gems/tree passives. You also have a chance to gain power charges on kill which might be enough to use power charges without the power charge on crit gem.

Trigger gems:
Cast on damage taken
It comes with a huge penalty (LESS damage) when used with a damage spell, that gets reduced when you level it up. On the other hand it increases the amount of damage you have to take before it gets triggered. You have two choices:
1) Keep it at level 1 and use it with enduring cry for some endurance charges that give 4% physical damage reduction per charge and a low level temporal chains or enfeeble to autocurse attackers (it might override your flammability curse occasionally though).
2) Level it. As you can't use spells that are of higher level than the CwDT i recommend maxing it to 20. It will take 3000+ damage to trigger but that can happen pretty quick in merciless. Use it as a second defensive layer with molten shell and decoy totem (in case you don't want to use spell totem - summon skeletons as distraction).

Totems:
Highly recommended and a must have imho: Spell totem + summon skeletons. Feel free to add a blind gem for additional defense. The boost in survivability is HUGE. If you have 6 skeletons up the chance of getting hit goes down from 1:1 when soloing to 8:1 (6 skels, the totem and you). That is a virtual evasion rate of 87.5%. It is impossible to get that rate in endgame even with the best pure evasion gear.

Blood Rage:
A very useful spell for CI chars. Every kill grants you a frenzy charge that increases your cast speed by 5%. The chaos damage penalty won't affect CI chars (don't use that spell as life char!).

Arctic Armour
A spell that is really helpful when facing enemies that do physical/fire damage with very fast attacks but low damage per hit like the voidbearers on docks or tentacle miscreations in the lunaris temple. Unless you build for a large mana pool it can only be used while standing still on max level; while moving the mana cost is too high and it will shut down very fast. If you can spare a single socket somewhere use it in voidbearers/titty bitches territory.
To sustain a high level AA while moving one needs a big mana pool (+3000), a maxed clarity and ~100manareg. One can bypass those requirements by using light warp as movement skill as AA doesn't have a higher mana usage in that case.

Movement skills
Used by some players to get out of tight situations. Witches mostly use lightning warp – reduced duration to get away.
As a dagger user I prefer whirling blades. Has no delay and doesn’t need a support. Lvl 1 is enough.
Use it if you have the free socket(s). Otherwise don't. Auras and attacks are more important imho.
Before opening boxes socket a Smoke Mine gem (lvl1) and lay the mine a bit away from the box. Click the box and immediately trigger the mine. That way you avoid getting surrounded by monsters.

CI/Life:
As long as you are leveling you need not look for a specific armor type. Instead focus on specific mods: Look out for gear with life on it; second priority is resistances. It actually doesn't matter if you wear an armor or eva based chest as long as you have the sockets for your gems on other gear pieces. The only restrictions you have to take into account are the stats requirement (you may not have enough STR for example to wear higher armor chests) and the socket colors for your gems.
Additional mods: Movement speed on boots. Useful offensive mods (aside from increased spell damage) would be faster projectiles (on the weapon). I wouldn't look for faster casting as this mod is pretty expensive. If you happen to get fc on a drop, fine. But don't spend huge amounts of currency on it. You can get the same dps increase for less currency if you only look for increased spell damage/increased critical stike chance for spells on a weapon.
Best shields to level up are Kite shields: Ceremonial Kite Shield (available at lvl 34) / Angelic Kite Shield (lvl55) / Archon Kite Shield (lvl 68). The 24 to all resistances help a lot to max resistances. As a life based char an Archon Kite shield may be even a good option for endgame as the low ES doesn't hurt for that kind of build. A CI should better look for high ES shield though.
Update: That advice only holds true for LEGACY kite shields. As of 1.1.0 only kite shields with 12 to all resistance will drop, making them no longer a best-in-slot option while leveling.

CI:
Get as many ES as possible, that means pure ES gear (once you made the transition of course; before that look out for HP on gear as the most important stat). If you are looking for a way to mitigate physical damage use granite flasks. You can’t afford to sacrifice your main “life” pool by wearing armour based gear.
Speaking of flasks: It is important that you have flasks that remove bleeding and dispels burning. Getting punctured or ignited is pretty bad for a CI as your ES will not regenerate. Start running while bleeding and the damage increases resulting in a very quick death. Removes freezing is another mod one of your flask should have. As of 1.1.0 you can encounter the corrupting blood mod on rare monsters. It stacks a bleeding effect on every attack YOU make. Without a remove bleeding flask this is lethal. Same goes for the bleeding stack that Dominus in his last form applies with his cleave attack. Don’t enter that fight without a remove bleeding flask.
Like I said you will need the eye of chayula to avoid stun. Instead of settling with anti-freeze mods on flask many CI chars wear (the very expensive) dream fragments ring that prevents freezing.

Life:
Looking at the colour requirements of the fireball setup (2 blue, 2 red, 1 green) it’s obvious to avoid pure evasion gear as chest as it would be very hard to get that many off-colours. The best option would be to settle with armour/ES hybrid as chest. By that one would avoid the high STR requirements of a pure amour (Astral plate and up), still enjoy a decent protection against physical damage and have some ES that boosts the mana pool with Eldritch Battery. The latter makes a pure ES shield with high ES a good choice. You need a big mana pool to sustain your spells while running auras, heralds and arctic armour late in the game.
You gotta have a flask that removes bleeding (see the info in the CI paragraph above)


Mentionable unique:

Great weapon for start and midgame. The +2 to level of fire gems gives a huge damage boost in those stages. Might even be viable in endgame though you might get better stats using high end wands/daggers or other uniques (not to mention the boost in survivability when using wand/dagger + shield).

Bandit rewards
Normal: help Oak for 40HP when life based; kill all when planning to go CI
Cruel: kill all for the reward point
Merciless: Kill all. Unless you plan on using power charges for endgame (if you happen to own void batterys for example) in which case help Alira.


Exemplary build
With all the gem choices it might be a bit confusing what combos to use. For the undecided here is the setup i use in endgame (life build):
Chest: Fireball - LMP - spell echo - life leech - fire penetration -
6th socket: elemental proliferation for clearing maps as the burn proliferation makes up for fireball not penetrating. That can be a bit tedious versus trash mobs as it takes longer to kill them all. Despite lower damage (for not using concentrated effect) the clearspeed is a bit higher and the gameplay a bit smoother. For bosses i switch ele.prolif. for concentrated effect.
Weapon: Lightning warp - reduced duration - faster casting
Helmet: clarity(maxed) - herald of ice - purity of fire - reduced mana
Shield: CWDT(lvl20) - molten shell(lvl20) - decoy totem(lvl20)
Boots: Herald of thunder - reduced mana - curse on hit - assassin's mark (or elemental weakness or enfeeble; depends on the party and the map mods)
Gloves: Fire trap - fire penetration - concentrated effect in a 3 link. Arctic Armour in the unlinked 4th socket.

How to handle reflect Just use fire traps. Traps don't reflect the damage back to you, so no risk using them.
You can also use spell totem + summon skeletons for diversion and careful shoot with the fireball at the edge of the mob aiming to get only 1-2 enemies. This works as elemental reflect is not as lethal as physical reflect. The portion that gets reflected back is mitigated by your elemental resist. The damage you suffer is therefore only
damage you dealt * 0.15 * 0.25 (assuming max resist without purity bonus)
In other words with a life or ES pool of only 3000 you would have to deal 80.000 damage to one shoot yourself. Happens only to Discharges that fully blast a huge relect mob.
You should also be able to do maps with elemental reflect as long as you don't spam Fireball into groups. Shoot once - retreat a bit or snipe 1-2 from the edges and use fire traps as primary attack.