Pros Cons
-Not very reliable on items -Can be mana hungry if not used right
-Great 1v1 -Quite slow
-Awesome escape ability with Rapple. -Takes a bit of skill to use correctly
-Can harras like crazy -Shes a friggin' spider
-No matter what she f*cks sh*t up.
-Good bushcheck with her W.

With Elise you will be jumping into the fray and really want to have some defenses. Thats why there are the Armor marks and the CDR. With that there is also an add of AP. This will help you in those early game skirmishes and be able to zone your lane opponent.

As you can see I have put the regular 21-9 for Elise. All of the offense points go into the AP section. This is because you are an AP champion. The 9 in Defense will add on to the rest of your defenses and help you early game.

-Starting Items-
-Boots of speed and health potions. This is pretty much the best way to start as the mobility allows you to farm and land harass. The potions allow you to stay in lane longer as you have no sustain.
-Doran's ring x2. These will provide some basic AP and HP to carry you to mid game. The mana regen also allows you to stay in your lane and be a little more trigger happy.
-Core Items-
-Glacial Shroud. This item will give you some Armor and CD, plus some mana. Instead of rushing Rylai's like a lot of people do this item will help you a lot more. Your abilities already deal tons of damage without many AP items. This will allow you to skirmish with other champions.
-Sorcerer's Shoes. This is just what any AP carry would get as it gives you MPEN.
-Rylai's Crystal Scepter. This item will give you a nice bit of HP and some AP. The slow will also allow you to slow enemies and catch them. Make sure to land spells in human form to slow.
-Abyssal Scepter. This item is perfect for Elise. It gives a nice amount of MR and AP, but its passive is the kicker. Lowering MR of enemy champions near you will allow your spider form to deal tons of damage. The MR takes out the need for a more defensive item like a Banshee Veil.
-Late Game-
-Frozen Heart. This item gives a an *** ton of armor and mana. The passive also is a great addition to Elise. You will be able to battle AD champions and get an advantage in team fights.
-Rabadon's Cap. This item is pretty much the bread and butter of AP. It dramatically increases your AP allowing you to shred your enemies.
-Zhonya's Hourglass. This item had armor also, kind of putting you into the tankier side. The AP is also a nice addition, but mostly the passive. Diving into team fights can get you into sticky situations. Initiating and becoming focused will happen a lot, so this passive will save your tail.
-Situational Items-
*SOON TO BE ADDED MOAR TESTING NEEDED*

-Elise's Q is my favorite spell ever. The damage it can deal as an initiator is crazy as it deals 8% current HP (without AP scaling!) The Spider Form of this Q can also deal a lot of damage to anyone being bursted down. This spell also makes you one of the best 1v1 champions. This is why you max this spell first.
-Elise's W is another great spell. This can be used to bush check, push, or just harass like crazy. Her spider form of this can deal crazy damage. It allows you and your spiderlings to attack faster (remember you deal extra damage as a spider!) If you have all 5 spiderlings you can mess some stuff up! This is why you max it second.
-Elise's E is all about utility. In human form she shoots a projectile that stuns enemies. This can be hard to land as you can accidentally tag minions. In spider form Elise shoots up into the air, untargetable. If she activates it again on an enemy she will jump down onto them. This is like the ultimate initiation/escape spell. RAWR. this is why you max this spell third.
-Elise's Ultimate. This is what makes Elise a crazy spider lady. It allows you to go from initiation AP caster to finisher AP bruiser.

-Early Game-
FARM FARM AND MOAR FARM. All you really want to do is farm. If you have a jungler, stay back then jump on them with Rappel and mess some **** up. Tag your lane opponent a bit with your Q to make them have to recall. If they initiate on you, stun them then burst them in your spider form. In other words, play smart.
-Mid Game-
By now you should have glacial shroud and sorcerer's shoes. Team fights will be breaking out all over the place. You job is to, in human form, either initiate or if possible tag squishies. ALWAYS CAST ALL YOUR SPELLS BEFORE ENTERING SPIDER FORM. THIS WILL GIVE YOU MAXIMUM SPIDERLINGS. After doing this, you then, in spider form, jump onto the squishies. If you cannot reach them from where you are, Rappel onto them and cast your Q and W. Spam your Q and stick to your champion. After this you can switch to human form and repeat the begging until everyone if dead.
-Late Game-
Just like mid game except you will want to be more careful of high damage enemies. You will want to sneak around and then jump right into the fray. You can either do this and attack from behind, or you can initiate and jump right onto the squishies after stunning anyone in your way. BEAT DAT SH*T UP.

Elise is an amazingly strong jungler. I will get to this section later as I am still expirementing with a good build. If anyone has suggestions HMU.

If you've gone this far on my guide without tearing your eyes out I congratulate you! As my first guide I would really appreciate any feedback on how I can make this better, thanks!