If your in a legion that takes these down quickly and at least four others are online who can see it, there's a more energy-efficient way to kill it. Before alerting, hit it slowly, using cages as it debuffs you and spamming it with sabs as it purges and lock it. Then alert it and spam with sabs as your legion mates hit it. In a legion as active as mine, it can still be killed in 8 minutes using this tactic.

Or someone else can just spam the entire time.

This is the tactic we've used, with so few that can see it. Works well.

Or, just use Improved Mind Influence...

Yep, cause any legion just happens to have a lot of genetarrs hanging around.