Denying

Denying is the act of preventing enemy Heroes from getting the last hit on a friendly unit by last hitting the unit yourself. Enemies will get reduced experience if the denied unit is not controlled by a player, and no experience if it is a player controlled unit. Enemies gain no gold from any denied unit. All allied units can be denied once they fall below a certain percentage of health: creeps, non-hero units, and illusions at 50%, heroes at 25%, and towers at 10%.

Denying Units
Allied creeps and siege units can be denied once they fall below 50% health. Denying an allied, non-player-controlled unit grants half experience to enemies within a 1300 range. To deny a unit, you must force an attack command on it. (By default this requires you to press 'A' and Left-click on the unit.)

Denying creeps is an excellent way to control a lane and gain a lead over your opponent. It not only prevents them from gaining gold and moves the lane towards your tower, it also denies your opponent experience which can cause a noticeable level difference in lane.

Some units such as 's Golem and 's Spirit Bear grant a significant gold reward should an enemy hero successfully destroy them. Denying these units is an excellent way to prevent giving the enemy free gold when the unit is unlikely to survive.

It should be noted that the Necronomicon Warrior will not trigger Last Will on a deny, though this is still a waste of the warrior's utility and is not recommended.

Denying Towers
Towers may only be denied once they drop below 10% health, and doing so will significantly reduce the global gold reward the enemy team gains from the tower's destruction. The difference between the standard tower bounty and a denied tower's bounty is as follows: Denying a tower will also prevent an enemy player from receiving the 150-250 bonus gold for the last-hit.

Denying Heroes
Heroes can also be denied under specific circumstances. A denied Hero will prevent the enemy from gaining any experience or gold from the kill, but will still lose gold upon death.

A hero under 25% health and under the effects of certain spells can be denied by an allied hero. The three spells that allow allied hero denial are:
 * 's
 * 's
 * 's

During, may be denied in a similar fashion if the sun is below 50% health.

If an ally affected by dies to its allies, it does not count as a deny. The kill gets credited to Winter Wyvern instead.

It is possible to deny oneself (commit suicide) in a variety of ways:
 * 's Pocket Deny
 * 's
 * 's
 * 's
 * 's  casted on an ally
 * 's  casted on an ally

It is also possible to deny allied heroes with some abilities:
 * 's
 * 's, 's , and 's Dominate can used on an enemy ranged unit that has a projectile attack in flight, and will result in the denial of an allied hero if the attack deals the finishing blow.

Lastly, a hero is considered denied if a neutral creep (or Roshan) dealt the finishing blow.