Warhammer 40,000: Inquisitor - Martyr

Firstly you need to reach level 20 with your battle sister to unlock you 1st banner type, the banner of valor. Different banner types will unlock at varying levels after that.

Then you need a banner to drop from enemies or chests in a mission. I was getting 1 or 2 a mission as drops.

Equip the banner to your belt slot, replacing grenades, shields etc. You deploy the banner by pressing . Banners only last for a short time. You only have a certain amount of charges available, you can result more in crates dotted around missions. Each banner has random skill sets that come with it to help your sister. There’s a cooldown timer after each use.

When you deploy your banner you will notice a coloured circular area around the banner, you need to kill enemies whilst stood in this area. I found this best done with a ranged weapon. The Achievement will pop once you’ve killed 500 enemies, you can check your progress percentage through the Achievement tracker.

You can spend passive skill points on upgrading banners, there’s a few upgrades for lowering cooldown times.

There’s also a perk available in the character section of the menu called Utility Harness, this gives you 2 extra charges to start with and 1 more charge resupplied from crates.

Occasionally banners will appear in the store.

Good luck with the Achievement.