Silence

Silence is a Shadow priest talent. It silences the target, preventing them from casting spells for 5 seconds, and acts against an interrupt against non-player targets.

• Any spell currently being cast will be prevented from completing when the target is silenced. The spellcasting of non-player targets is also fully interrupted, allowing targets that are immune to silences, such as bosses, to still be interrupted by this ability.
• Silence is not affected by the global cooldown.
• In PvP against casters, this can simply disable them for 5 secs.
• In PvP when used against paladins, they can use Divine Shield to remove the Silence effect. So preferably it should be used when they have already popped Divine Shield. Warlocks with their Felhunter out can cast its Devour Magic on themselves to remove the effect.
• In PvE, there are many caster-type mobs that can't be pulled like normal mobs. Pulling with Silence will cause them to come to you to engage in melee, since their ranged attack (magic) is disabled. It can also stop a mob's healing, which is sometimes very useful.

• Silence is a common Priest spell in Hearthstone. The flavor text reads: "Reserved for enemy spellcasters, evil liches from beyond the grave, and karaoke nights at the Grim Guzzler."