User blog comment:General Vincent Fardesto/HLF Armor/@comment-25405125-20150327114910/@comment-26230550-20150327120436

They detect an incoming projectile and will instantly activate and send out a disruptor wave to block out magical effects as well as plasma.

The other time, it deploys a projectile launcher that destroys the incoming anti tank round, (EX: RPG, Tank Round) and will destroy it within 3 feet.