Increase the critical strike damage bonus of Mortal Strike, Slam and Overpower by X%.
Impale is a Tier 3 talent in the Warrior's Arms tree.
It increases the damage bonus of critical strikes with special attacks. Impale does not affect auto-attacks ("white damage").
Impale increases your critical damage for special attacks by an additive 20%. Essentially, a critical strike with any special ability (such as Heroic Strike, Mortal Strike, Slam, etc.) will do 220% damage. This is an excellent talent for any crit-oriented warrior. It is important to note that this does not affect "regular" critical strikes, also known as white critical strikes that result from auto-attacks and not special abilities.
Example 1 (without Impale)
Your Heroic Strike hits for 500.
Without having talent points in Impale, the critical strike bonus would be (500*200%) = 1000.
With one talent point in Impale, the critical strike bonus would be (500*210%) = 1050.
With two talent points in Impale, the critical strike bonus would be (500*220%) = 1100.
Example 2 (with Impale)
If your Bloodthirst hits for 600,
Without having talent points in Impale, your Bloodthirst critical strike would be (600*200%) = 1200.
With one talent point in Impale, your Bloodthirst critical strike would be (600*210%) = 1260.
With two talent points in Impale, your Bloodthirst critical strike would be (600*220%) = 1320.