Jake's DOTA mechanics of the day.

Dummy units:Useless units used to cast spells. A good example is SA's smokescreen, where you can see the dummy unit by holding the Alt key when there's a smokescreen. Others would be Broodmother's web, Slayer's Light Strike Array.

Epicentre:
After 2 seconds of channeling, a dummy unit casts repeated thunderclaps on the area where SK is. The dummy unit continues casting even after SK is dead, cycloned or hexed. So be sure to run away when you see that SK with a blink dagger approaching you!

Triggers:Events, used to simulate spell effects. The triggers can be non-magic based. Usually does exact damage. (eg. omnislash, brain sap, laser)

Chronosphere:
Pauses all units in the AOE every 0.X seconds for the amount of seconds the sphere lasts. Trigger based spells (eg. aphotic shield, omnislash) will still take effect in the AOE. Wards will still attack in Chronosphere.