Never heard of blastr, but can confirm NIP 65 is powerful.

In my case, it lets me configure a bot by just giving it one "seed relay". From there, it looks up my kind 10002 Relay List and starts listening for commands on those relays.

Cool thing is that it's self-adapting. My client can publish a new kind 10002 list, then all other clients (bots) who follow can update their relay list on the fly.