A note on fluff
The purpose of this forum is to discuss tactics, not fluff. It is not legitimate to criticise people's choices in this forum if you happen not to like something about the fluff. If you would prefer not to play against people using two lash daemon princes then that's fair enough, but it's not a tactics issue. Talk about it somewhere else.
However, it is legitimate to look for advice on how to use a fluffy army. If you are limited to a particular selection of units due to fluff or for any other reason, like the price of plastic spacemen or just for the challenge of trying something unusual, then you can expect to receive advice on how to use that stuff. You should not be told to buy obliterators and daemon princes to cast lash.
This forum takes a neutral position on anything other than tactics. If you choose to limit yourself in some way then that is your right, but don't expect others to do the same thing.