You might know about this but if not here's how it works. Get in a group for Invasion. Tag everything you see. Do this until Stage 3 starts. Leave group, log out. Log back in. You are in Stage 1. See step 1; rinse, repeat. 10 levels per hour and more shards then I know what to do with. I'm at 500+ right now. GL out there. You can only loot the satchel from Stage 2 once.