Dominion is a Halo 4 War Games gametype, similar to Territories. In Dominion, there are three points on each map that either team can “Base Capture” and take over as their territory. As the game progresses, teams unlock a variety of ways to defend their controlled areas against the other team coming in and taking control of that point. If a team captures all three points the game changes, and if that team eliminates all the members of the opposing team it’s game over and a win.
Following is a Halo 4 walkthrough strategy of Dominion on Longbow by Bravo.
Here is the original gameplay and Halo 4 Developer Commentary by Josh Holmes on Dominion by IGNentertainment: