Queen of Pain is a ranged intelligence ganker. With incredibly high burst magic damage and mobility, she makes for an excellent mid hero who can quickly gank the side lanes and burst down squishy heroes with her three offensive abilities, two of which deal AoE damage.
Skills
Shadow Strike is skilled once early on for harassment purposes but typically maxed last.
Blink is skilled first for escape purposes but maxed second.
Scream of Pain is maxed first despite being skilled last.
Sonic Wave tends to always be skilled (levels 6, 11 and 16).
Items
Starting Items: Tangos, 3x Iron Branches, Mantle of Intelligence.
Early Game: Bottle, Power Treads, Magic Wand, Null Talisman.
Core Items: Orchid Malevolence, Aghanim's Scepter, Black King Bar.
Luxury Items: Scythe of Vyse, Veil of Discord, Shiva's Guard, Bloodstone, Eye of Skadi, Ethereal Blade.
Situational Items: Boots of Travel, Linken's Sphere, Dagon, Monkey King Bar, Desolator, Mjollnir.