Spellcloth

Spellcloth is a high level cloth crafted by tailors. It is used to create set items with bonuses to spell power.

Source
Spellcloth can be created by tailors of skill 350. The materials are:

A tailor must be anywhere in the Netherstorm zone to craft Spellcloth. Tailors with spellfire specialization obtain two Spellcloth from the materials for one.

The pattern is sold by in Shattrath City for.

Note: As of Patch 3.0.8 there is no longer a cooldown on Spellcloth.

Warning!
Crafting Spellcloth spawns a level 70 Angered Nether-wraith (Arcane Elemental), which drops 1-3 Motes of Fire and 1-3 Motes of Mana, giving a sort of refund to players capable of killing them. You can summon the elemental anywhere in the map, but it is advisable to fight in a populated area, where someone might help you kill it. Area 52 guard NPCs will now engage the elemental. The elemental channels Arcane Missiles and cast a powerful Shadowbolt after a while. Although not elite, killing it solo is difficult for characters not yet 70, or those unprepared to fight it. Before engaging equip any arcane-resistance gear, if available. Mages should have up the Mana Shield plus Dampen Magic, and save the Counterspell for the dangerous Shadowbolt, towards 20%-30% of the mob's hp. He seems to be weak against Holy magic.

Mages can also Spellsteal a buff from nearby Shaleskin Flayers that reduces spell damage by 50%, one charge. Alternatively, they can cast a portal beforehand and just jump through it.

Tailoring

 * Boots of Blasting
 * Boots of the Long Road
 * Bracers of Nimble Thought
 * Manaweave Cloak
 * Mantle of Nimble Thought
 * Spellfire Bag
 * Spellfire Belt
 * Spellfire Gloves
 * Spellfire Robe
 * Spellstrike Hood
 * Spellstrike Pants
 * Sunfire Handwraps
 * Sunfire Robe

Engineering

 * Gnomish Power Goggles