Halo Wars 2

This achievement will likely come naturally while playing online matches as The Arbiter, but it can be very quickly in solo Skirmish matches against the AI on Easy. If you're taking this route, head into the Skirmish lobby and make these setting changes:

• Gametype: Domination
• Starting Supply: 9999
• Starting Power: 9999
• Skulls: Emperor

Now choose The Arbiter as your leader and begin the match (the map choice does not matter). Once the match starts, quickly move around the entirety of the map, building firebases and mini-bases. Continue to build upon and upgrade the buildings and turrets of your bases so that you earn enough Leader Points to unlock the Stasis I and Power Surge I abilities.

Once you have access to these two abilities, begin building as many Grunt units as your population limit allows. When they are all huddled up on the battlefield at the Local Rally Point, use Stasis I to trap your own units (you should be able to net 10-15 here). Now wait until the ability cools down - the Power Surge I ability and Emperor Skull will expedite the cool down tremendously - and then use it again and again on your units. It should take no more than five to ten minutes to trap one hundred units, at which point the achievement will finally unlock.