Assist

The Assist Medal is a Firefight medal in Halo 3: ODST and a multiplayer medal in Halo: Reach.

Description
It is represented by a red and white Yin and Yang symbol in the center of a 5-pointed gold star. It is awarded exactly the same way 'assists' are given in traditional multiplayer, damaging an enemy that is finished off by someone else. It is a fairly common medal in 4-player Firefight.