Faction Black-list

(All of the following is a hypothetical situation as it's the best way I can explain it)

When I play Endless Space I like to play with a small number of factions to keep the game quick. I also like to play with random factions because I find it more fun. But every game I play I lose to faction X and don't want to play against them. The only at present to guarentee I'm not playing against them is to choose all the factions.

However, if there were a blacklist where I choose "random faction just not faction X" my problem would be solved.

(End of hypothetical)

I had this issue with Endless Legend as I like random but kept losing to the Necrophages. I don't think this would be much work but I know very little about game design so yeah.