MACRO use

Casts the first spell for which the options are true. /use [options] item name or item link or bagID slot or invSlotID or spell name

Arguments
The clause value is interpreted as either:
 * item : The name, or the item link, of the item to be used.
 * BagID and slot : The bag the item is in (0 is backpack, etc...), and the slot number containing the item, starting at 1; e.g. "0 1" would use the first item in your backpack.
 * invSlotID : The slot on your character in which to use an item.
 * spell name : Name of the spell to cast

If the clause value is the name of both a spell and an item that at some point was in your inventory, the /use command prefers to use the item.

Details

 * As of Patch 2.3.2 cast command toggles toggleable abilities on and off. Prefixing the name with an exclamation mark prevents this. Examples of toggleable abilities are Stealth and Shoot.
 * Note that you can use /use to cast spells, and many of the /cast details apply.