For the rune i decide to take full flat because i think overlvl it useless because of the ap item. Flat it's useful because even if you start with boots and potion you can still make significant damage to the enemy.

I build my Elise top a little tanky because if you get vs champ as olaf or other champ that make nuke damage you need that hpfor survive. I rush the Rod of Age for being able to harras the enemy champ to get him low hp and after nuke him in spider for by getting the more mana possible. The Hextech Revolver is for the spell vamp so you can heal in spider form without using mana. The Lich Bane is for augment the damage because of the passive and the movment speed can be usefull for chase a enemis in spider form. The other item are main mage item for the passive of slow of the rylai and the passive and ap of rabadon.

For the skill i decide to start with Neurotoxine/Venomous Bite(Q) to deal significant damage and aras to the enemy. My second spell Volatile Spiderling/Skiterring Frenzy(W) is for augment the aras and give the ability for Elise to heal up on minion and to heal in fight. The last spell Cocoon/Rapell(E) is for stun the enemy to make the spell easy to aim and rapell is for jump fast on range target or go back on enemy minion if you push to far behind the enemy minion and get gank. I decide to max my Q first to make strong damage and because the toper are normaly tanky champ and the 2 Q of Elise make % of hp of the enemy so it dont matter if the guys have 3000 or 1500 hp. As second spell i choose the W because between him and the E it was the most useful the E was only getting the cooldown down.

For my 2 summoner spell i like to take ghost and ignite. I always hate flash for go out i think it only usefull for pass through a wall i like ghost because it give a very good boost of speed and you can pass trough minion with it so if you are in lane and getting gank you dont only teleport 2 inche closer to your tower you can run very fast to the tower and pass trough minion and after whacht the enemy triyng to pass trought all the minion for follow you. As second summoner spell i choose ignite because it can be very useful for finish enemy as they are triyng to get away and can be useful if you know your enemy have lot of life steal or that he can heal himself you call ignite on him and reduce all his healing for 50% and make true damage to him as the same time.