[ the mandalorian isn't surprised. he didn't know until he asked his rescuers. ]

They're heavy weapon battle droids, integrated with rocket launchers and wrist blasters built-in. Bounty droids like you are designed to be fast and efficient with minimal targets. B2's are large and slow, and can wipe out hundreds in a minute.

...And so they did. Everyone died. Only I was saved by the Mandalorians.