This is pretty easy done in big BGs like AV/IoC. For example at the side of field of strife in AV where you wait untill a bad geared player (less then 100K HP for example) comes a long. Might require few tries to find enough nabs and make sure ou don't get caught. Or get lucky in a WSG where the opponents are so bad you are farming them at their graveyard. Just don't get too cocky, 19-1 happens quite a lot.