Sensory deprivation

Sensory Paralysis is the ability to cut off people's senses: sight, taste, smell, touch, and hearing. Alec from the Volturi has this power, and it is known as one of the most powerful gifts in vampire history.

Description
Alec can apply it to more than one person at the same time, and it takes the form of a slow white mist -like fog- that gradually makes its way towards the victim. It is the opposite power of Jane's gift and is equally powerful. The Volturi would use it to paralyze their victims if they felt kind towards them, so that they wouldn't feel the pain of being killed. It can be used like an anesthetic. But this doesn't happen often. The only example given is: If there are witnesses to a unforgivable crime, Aro may feel kind to them, as they have done no wrong; they have only witnessed and not committed a crime. But they still need to be destroyed.

When his power touches Bella's shield, she says that she can "taste" the power and that it has a dense, sweet, cloying flavor. It reminds her dimly of the numbness of Novocain on the tongue. He can also manipulate the effects into merely incapacitating few senses, or incapacitate them all at once.

Limitations
Although this gift is powerful and works on an entire group at the same time, it takes some time to take effect on the victim. During this time, the enemy can either attempt to escape or attack the caster before his power takes effect. It also only lasts for as long as he is able to focus. For this reason, Alec is often protected by the Volturi guard, allowing him to use his power without interruption. In Breaking Dawn, Alec attempts to cut off the Cullens' senses and those of their allies while they talk about the punishment to be given, but thanks to Bella's shield, his ability is deemed useless.