When it comes to champions that can be wildly entertaining to play, and also have excellent utility when playing alongside newer players as they learn the ropes, Lulu is second to none. Usually the highest compliment I can be paid is when a member of the opposing team feels the necessity to complain that "if that *&^$ing Lulu wasn't there I'd have killed you", or to see an ally wreck the entire team while wearing your Wild Growth, Whimsy, Auras, and Pix along for the ride glitter-blasting the entire team.

This is purely a functional guide, not intended to be the end-all 'how to play Lulu', simply simply an overview of how to build a support oriented Lulu with good sustain, survivability, and the ability to help your team dominate teamfights.

The focus of this build is primarily about building a very utilitarian support Lulu that is still quite survivable if focused, and devastating if allowed to freely assist DPS champions.

So come on, you: let's dance!

Pros:
Impressive survivability with shield, speed buff, and if needed, ultimate for yourself or others
Glitterlance is an outstanding poke, viable farming tool, and a devastating slow
The knock-up from Wild Growth is phenomenal CC when timed right
SQUIRREL!!!
Seriously: polymorphing and then stomping opponents NEVER gets old.

Cons:
Slow, unless you are burning mana to cast Whimsy on yourself.
Mana hungry at lower levels
Self-casting spells in team fights to stay alive is usually selfish
NO HEAL - doesn't do well supporting aggressively played champions with limited sustain

I typically run a mix of 0/9/21 with different Utility setups depending on starting items desired. Early AP through the offensive side can be beneficial if you're looking to push a lane, or provide a more stout shield with [Help, Pix!], but generally the Veteran's Scars flat health and the gold per 10 form the utility side is most desirable.

[Edited 5/10/12 to add]
I've also been experimenting with a modified 9/9/12 mastery page with this build. While exceptional at nothing, for a balanced AP support character I have had some success starting with 9 in the offense (+4 AP, CDR, and 10% MrPen), 9 in defense (Up to the +30 health from Veterans Scars) and 12 in utility that allows all 4 points of gold per ten (+2 GP10) to be filled. More on this to come.

[Edited 9/22/12]
The 9/9/12 Mastery page is an excellent addition to early game poke-based AD Carries, as the combined poke and damage early on can be worth giving up 9 points from a standard 21pt utility tree, especially since you don't have to sacrifice the passive Gp10 skill.

.
R >> Q >> W >> E

The flat damage stepping up Glitterlance at each level make you very good at poking, but causes you to be rather mana deficient when it comes to shielding allies and disabling enemies. All the utility required is gained at Lvl 1 of this skill.

My reasoning behind upgrading Whimsy/Polymorph sometimes before the more defensive Help Pix spell is that mobility often is more valuable to the carry you're supporting to either escape, or snag a kill early, and the brief disable Polymorph provides can often shut down incoming damage more efficiently than shielding a portion of it.
The little bit of damage and visibility that Help, Pix! provides if used on enemy champions can be quite handy, but it really only shines if followed up by a well placed Glitterlance. I'll go into more detail about this combination, but it's one that uses significant amounts of mana, and in my opinion that makes the two less useful early in the laning phase without any mana regen items.

That said, Lulu has the strongest damage mitigation throughout the early game by shielding an ally with Help, Pix!, so if your AD lane mate, or if need be yourself are taking some abuse in trades, this is where you should prioritize your mana expenditure.

I'm a Clarity user at heart, and with the mana hungry carry champions I'm usually laning with, it actually shines. Heal is obviously a viable replacement, but usually that's snagged by my carry, so I move on without it. If you want a dominant early lane, go with this and level Glitterlance, otherwise, the more standard approach is preferre.

Flash has obvious utility, simply because it's usually the best tool instantly closing or creating a gap, and can be done over terrain.

Exhaust is my preferred second spell, especially when adding the -10 Armor/MagicResist shred included from the Offensive Masteries (although if you have an 0/9/21 page, that stat is not worth giving up Veteran's Scars or a full 21pt Utility tree for.

Although Lulu scales well with AP items, this usually comes at the expense of survivability. I've found with my play style that being actively involved for the duration of the fight, even with reduced AP fueled destruction/shielding, can be more decisive in teamfights, but obviously YMMV.


Starting with Boots can actually work somewhat well, but also means you'll find yourself having to be rather sparing with spells, and limits the ward output you're able to do early. This can still work very well, as boots can give Lulu huge lane presence early. Otherwise, starting off with a Faerie Charm is fairly standard, and if you're pushing for an early kill, you can even get away with getting only one ward and a Rejuvenation Bead


For the first trip, I'm getting at least a Regrowth Pendant, hopefully for a Faerie Charm, or ideally a complete Philosopher's Stone for that first trip. The Mana/Health Regen early enables you to be a constant presence while laning, and you can decide in which capacity as needed (poke/harass, shield/defend, haste/kill snagging for your carry).


Second trip, I'm working towards Tier 2 Boots as well as a Heart of Gold.
Mercury's Treads are an obvious preference because of the tenacity and early MR.
Heart of Gold provides survivability in the form of health, Gold per 10, and builds into the Locket of the Iron Solari down the road.

- Against an AP heavy combo, picking a pair of Null-Magic Mantles isn't as absurd as it looks, as both build into very handy items


Following that, a Kindlegem adds some health, and building the Philosopher's Stone with it towards a Shurelya's Battlesong is an early priority because of mobility that active provides.
An Aegis of the Legion continues with affordable defensive aura goodness, and provides some armor, MR, and health to boot.
An Emblem of Valor provides even more health regen, some armor, and yet another valuable aura. This will eventually be part of the Locket of the Iron Solari, but at this point you're pumping out useful auras for team fights, and hopefully surviving each encounter, since you now own three Ruby Crystals for health, two Null-Magic Mantles, and two sets of Cloth Armor.

While the responsibility of acquiring an Aegis of the Legion may fall to a different player, if nobody else is building one, Lulu might as well, since the rest of the build is also focused around being useful in teamfights by sticking around AND using abilities.

Late game, building some ability power along with yet another valuable aura come in the form of a Will of the Ancients. This in addition to casting Whimsy on a friendly mage just adds to potential devastation, and the spell vamp, especially if stacked, is nothing to sneeze at.
Finishing the Locket of the Iron Solari provides yet another active ability along with an improved aura. The late game output of the locket isn't as impressive as if it were rushed earlier, but on countless occasions this has made the difference when extricating an imperiled squishy champion on my side. Having yet another shield that soaks up to 230 dmg to throw around as your team initiates is always welcome.



Substitutions and Situational Items

- Situationally Boots of Swiftness provide better map coverage, but this often necessitates buying an Aegis of the Legion or other MR item early. Not recommended against a team with effective mages or CC champions, but it's certainly a viable option.

- Valuable defensive items can include:
Frozen Heart against AD champions, as it provides some hefty armor, slows enemy AS, and provides some valuable mana and CDR.

Guardian Angel if, for obvious reasons, the other team has decided they're tired of behaving like doomed squirrels every team fight.

Force of Nature provides significant MR, along with even more health regen, and some movement speed. Not usually ideal, but sometimes.

Spirit Visage is affordable, provides some health, MR, CDR, and stacks well with the health regen elsewhere in the build.

Abyssal Mask provides MR from the Megatron Cloak, AP from the Blasting Wand, and that MR Reduction. If those are what you need, it's a great finishing item.

Rylai's Crystal Scepter provides a ton of health, and mostly provides ability power and some limited slow if you find yourself casting on enemies instead of allies.

Rabadon's Deathcap simply because the hat looks good on her. As she stands over the remains of her foes.

Early game, the movement speed and ability power bonus that casting Whimsy on a teammate provides can result in kills from otherwise less awesome circumstances.

A well timed Polymorph functions essentially as a combined SLOW, SILENCE, and BLIND. (Think about it, it's all there - plus, you get to watch a big mean Cho'Gath turn into an adorable little squirrel). While usually this can enable your team to nuke down an opposing squishy champion, often it's useful enough to put a stop on an opposing tank/melee champion disrupting your own team.

Casting Wild Growth on allies, or even self-casting for the crown control utility can be a good way to isolate opponents. This in combination with a Polymorph, then the slow from your Glitterlance will cripple an opponent for a large amount of time if you're allowed to complete the combination, and hopefully allow a team member to focus and decimate them. That's assuming there isn't a teammate's CC to chain with this.

Finally, the most useful trick Lulu has, and one that make me consistently giddy when it works well, is combining her Help, Pix! and Glitterlance. By casting Help, Pix! on any unit, you've acquired a new anchor point from which to launch your Glitterlance.
This can work one of four delightful ways:
- Casting Help, Pix! on a friendly champion. This shields them, and allows you to slow enemies in their path without necessarily exposing yourself.
Result: Yay!
- Casting Help, Pix! on an enemy minion. You get some damage output on that minion, and you've just increased the range of your Glitterlance
Result: LOL [If you're ahead in a lane enough to freeze it, this just further extends the radius you can zone an enemy from]
- Casting Help, Pix! on a friendly minion. This allows said minion to tank more damage, but more importantly your have an anchor point that will happily charge towards the enemy. Some of the most awesome kills I've gotten are from this.
Result: Hilarity [This is seriously fun, but may lead to running yourself out of mana quickly, and stealing farm]
- Casting Help, Pix! on an enemy champion. Damage, visibility up front, and the glitterlance can hit them as they flee. This makes it impossible to escape Lulu's clutches.
It gets better when you land the Help, Pix! on a retreating enemy, who then exposes their teammate who is just clinging to life. Glitterblast to the face.
Result: ROFLCOPTER [When Morello mentioned trying to design some support champions with amusing mechanics to reward playing that position, I think this is what he had in mind]

Figuring out which exact variation of a build may take some time to work out, and it takes some time to be really on top of her cooldowns to be maximally effective in teamfights, but so long as you're aiding the right teammate while glitterblasting every opponent in the face, the impact Lulu has is unmistakable.



Questions/Comments are welcome below. This build is current as of the Kha'Zix Patch
- I'd rather focus on more informative guides than ones with fancy dividers, hopefully I'll get more chances to run Lulu in ranked play and further improve this guide!