Shiv

From WoWWiki

Shiv
Shiv Instant 5 yd range 20 Energy Performs an instant off-hand weapon attack that automatically applies the poison from your off-hand weapon to the target. Slower weapons require more Energy. Awards 1 combo point.
Usable by
Class	Rogue
Properties
Type	Offensive
School	Physical
Cooldown	None/Global Cooldown
Other information
Requirements	Melee Weapon

The pain from the blade is the least of your worries.^{TCGTDP 87}

Shiv is a rogue ability, learned at level 70 for 12 60 .

While at first glance, Shiv may seem like an underpowered attack ability, it has several unique properties that make it very useful to smart Rogues.

Poison Application

One of the most obvious advantages of Shiv, instant perfect poison application is useful in a variety of ways:

Stacking Deadly Poison for easy 5-pt, 5 poison stack Envenom.
Application of Crippling Poison, Mind-Numbing Poison, or stacking Wound Poison in PVP.
Application of Instant Poison or Anesthetic Poison, to mitigate the loss of dps over other skills.

Energy Cost

With its relatively lower energy cost, shiv can build combo points very quickly. Useful for fast stuns, or when you need to get Slice and Dice up.

The energy cost of the ability is entirely dependent on the speed of the off-hand weapon:

20 + (10 * weapon speed) = Energy consumption

So, with a 1.8 speed off-hand:

20 + (10 * 1.8) = 38 energy

Managing avoidance in PVP

Though it is not explicitly mentioned in the tooltip, it has been confirmed many times that Shiv cannot be dodged. It may also be unable to be parried or blocked. This makes it useful in PVP situations when your opponent is low on life and uses a temporary avoidance boost (such as Evasion or Ghostly Strike).