Executioner

Executioner is a Generic Talent that grants increased Basic Attack damage when paired with crowd control. All you have to do is hit the disabled Hero once and you gain the increased damage right away. It's an easy way to deal quite a bit more damage consistently, the only downside being that the Talent is often on Heroes with limited, meaning you need good team synergy to make the Talent work. Heroes like Jaina and Arthas can give you near constant uptime, if they're on the same target as you. Bear in mind that this Talent does not affect some crowd control effects like Silence or Blind.

Mechanics
Base version of Executioner is an attack modifier, which triggers when a Basic Attack impacts on a Stunned, Rooted or Slowed enemy Heroic Target. As such, Executioner cannot trigger, if the target Evades the Basic Attack or the attacker is Blinded at the moment of impact. Executioner also cannot trigger from (permanently) Unstoppable or non-Heroic targets. However, only triggering is conditional and when triggered Executioner provides a passive bonus to Basic Attack damage, which affects all targets.

Damage bonus from Executioner stacks additively with other offensive damage modifiers and only affects Physical Damage dealt by the Hero's Basic Attacks. Splash and Cleave effects can usually benefit from Executioner's damage increase.

Old versions
Originally Executioner affected all enemies, but the damage bonus applied only to the Basic Attack that triggered it.

Base Version:

 * Greymane
 * Sgt. Hammer
 * The Lost Vikings

Modified Version:

 * Anub'arak's level 13 "Acid Drenched Mandibles", causes his Basic Attacks against disabled enemies to grant 70% Basic Attack damage for 3 seconds.
 * Deathwing's level 13 "Fire and Fury", causes his Basic Attacks against disabled enemies to deal 30% more damage and reduce his Basic Ability cooldowns by 0.5 seconds.
 * Mei's level 1 "Heat Transfer", causes her Basic Attacks against disabled enemies to deal 33% more damage.
 * Muradin's level 7 "Give 'em the Axe!", causes his Basic Attacks against disabled enemies to grant 50% Basic Attack damage for 3 seconds.
 * Samuro's level 16 "Merciless Strikes", causes his Basic Attacks against disabled enemies to always be "Critical Strikes".

Removed
These Heroes no longer have Executioner as a talent option:
 * Illidan (old version)
 * Kerrigan (old version)
 * Raynor
 * Tychus (old version)
 * Valla
 * Xul
 * Zeratul (old version)

Similar effects
Following Talents have a similar functionality in increasing damage when attacking disabled enemies, but do not affecting or limited to increasing Basic Attack damage:
 * Cassia's level 16 "Martial Law", causes her Basic Attacks against disabled enemies deal an additional 3% of the target's max Health as damage.
 * Chromie's level 5 "A Proper Greeting", causes damaging a disabled enemy to increase all her damage by 25% for 5 seconds.
 * Lunara's level 16 "Unfair Advantage", causes "Nature's Toxin" to deal deals 60% more damage to Heroes that are Slowed, Rooted, or Stunned.
 * Orphea's level 1 "Ancestral Strength", causes her non-Heroic Abilities against disabled enemies to deal 15% more damage.
 * Raynor's level 1 "Ace in the Hole", causes his "Penetrating Round" to deal 25% more damaged to Stunned and Slowed enemies, but not Rooted ones.