Purge

A Purge is a type of ability that causes a drastic slow in movement and attack speed, and has a gradual movement speed restoration over the duration of the effect. At the moment, there are 5 Purge Abilities

=How Purge Works= A Purge on a hero will initially remove most debuffs on allies, and buff on enemies. If cast on an enemy unit, for the duration of the effect, it will slow the their movement speed, and can slow their attack speed depending on the specific purge.

Most Purges on Heroes will slow a unit down to an initial 100 MS, after which they will gradually regain speed for the duration of the effect. The rate they regain speed is determined by how long the effect last, an attribute called the update frequency, which is the number of ticks which movement speed is restored. The value ranges from 1 to 5.

For example, Diffusal Blade's Purge has an update frequency of 5. If the unit had 350 movement speed and was Purged, they would gradually regain speed in the following way. 100/140/210/280/350. The way the speed is calculated is that your speed is reduced to 0%, and you gradually recover a percentage of it every tick. For a update frequency of 5, you recover 20% per tick, for 3, you would recover 33% per tick.

Demonic Purge, Stone Gaze, and Unstable Current will in addition reduce attack speed by 100, and will gradually be restore in the same way as movement speed. A Diffusal Blade Purge, Stone Gaze, and Demonic Purge cast on a non-hero unit will be paused for the first 3 seconds of the duration. A Diffusal Blade Purge will instantly kill summons and illusions, a Satyr Trickster Purge will do 400 damage to summons and illusions.

=List of Purgeing Abilities=

Diffusal Blade
=External links=
 * Mini Guide to Purge: http://www.playdota.com/forums/showthread.php?t=406048