Many Items and Abilities will talk about doubling the damage of Basic Attack and their are a few things to keep in mind with these abilities. Items and Abilities that double your damage only double Basic Attacks. They do not work with abilities unless that ability makes you perform a Basic Attack. You also can't double a double. Only one effect that doubles (or sometimes triples) the damage of a Basic Attack can be in effect at any time. Critical Hits will however stack to double the damage a second time.