This is my first guide and i wont write much ;)
just test this build and give me a short feedback

its more fun then the Rageblade into Deathcap into Lich Bane builds ;)

Your main dmg will be magic-dmg so i suggest Greater Mark of Magic Penetration
you can also use Greater Marks of Desolation

i love the dodge on nida so i use Greater Seal of Evasion
well u can use Mana Reg Runes too, but normally you wont need them

nida is very squishy so i take Greater Quintessence of Health
Armor or Magic Pen Runes would be good too

First Item Doran's Ring
you will need the life and the mana reg in the early game

Second Item Boots
i normally take Mercury's Treads
but if the other team has much ad Champs i prefer Ninja Tabi
also a good choice are Sorcerer's Boots

Third Item
"The" Coreitem for all Nida's Guinsoo's Rageblade

Fourth Item
First Hextech Gunblade
begin with Hextech Revolver and then the Bilgewater Cutlass
perfect Hybrid item like Rageblade but with an insane life steal and spell vamp
normally a nida jumps into the fight nukes and then runs out and heal herself
with a Gunblade you can easily stay in the team fights and do much more damage
but if you have to heal yourself....just do it ;)

Fifth Item
Is the first defense item Banshee's Veil

Sixth Item
The Second Hextech Gunblade

Last Item
Second def item Guardian Angel its just the best late game item

you can switch Banshee's Veil and Guardian Angel
if the enemy team doesnt have much ap dmg or stuns u just buy another Hextech Gunblade

Good Summoner Spells:





I use and
nida dont really need Ghost because with Cougar and the passive is she faster then the most champs
and nobody can catch nida in the jungle :)