Pls find sample snippet of RTBH:
You get a route from omunity x123:666 from customer ,while importing from customer you give this statement
to change the next-hop as discard while advertising in your core..if you want u can add user defined community y with then community add knob for easier tracking of these routes(in this way u know which community as a whole is blackholed if you are only blackholing only specific prefixes from that community) .
set policy-options policy-statement for-rtbh term 1 from route-filter x
set policy-options policy-statement for-rtbh term 1 from community for-rtbh(123:666)
set policy-options policy-statement for-rtbh term 1 then community add to-core(community Y)
set policy-options policy-statement for-rtbh term 1 then next-hop discard