This is my second build and I didnt put a description on the last one but im going to try this time.

The reason for my masteries is I like to use clarity for the begining when she runs out of mana fast and I like flash for getaways and its good for her grab to get in range or past minions.

The reason for my runes is you want cooldown for her ult and spells to have them at the right time and to have alot of ap for your spells damage.

The same reasons aply for the items and if you want you can switch one zhonyas or archangels for a mejais if your doing realy good at the begining. If you need you can also switch an archangels for a Rod of Ages or Abyssal scepter if you need the hp or magic defence.

I play her as a support and i like to go mid if i can but shes also really good with a partner and one tip for first time players you want to trap them before singularity for max damage only use it the opposite way if you need to slow them to land the trap. With your ults its hard to land so you want to think about where they are going to go before using it. You also want to use the shield as much as possible because it blocks quite a bit of damage and can save you sometimes.

Well thats my description hope it helps even though i dont think i did very good with it but please tell me if there is anything wrong with it. Thx :)