Halo Wars 2

This achievement will come naturally over the course of your time playing the many Multiplayer, Skirmish, and Blitz modes. As mentioned before, there is no real reason to grind this out unless you don't want to get involved with match-made Multiplayer or Blitz games.

So, if you want to grind this out against the AI in a Skirmish match, head into the Skirmish lobby and start a Strongholds game immediately with Captain Cutter as your Leader. There is no need to make any additional setting changes.

Once the match starts, open up the Leader Power menu and use the Restoration Drone ability. Now quit/end the match. When you return to the lobby, start the match again and repeat this process as needed. It may seem questionable, but this method will make it so that you're technically casting a Healing Leader Power within a minute and a half of each other as opposed to having to wait several minutes of cooldown before being allowed to cast it again in-game.

In the end, regardless of how you go about this achievement, it will finally unlock after casting 100 Healing Leader Powers.