Question about spectres

New to spectre build. What do you do when your spectres die in a map or during boss fight?

Do you just try to finish the map/boss without the spectres?
Or do you just give up and go raise them in the specific map again?

Man, I swear I don't get the rudeness of most of the people who play this game. Of course they must be thinking that you raise temporary spectres from what's available at hand but I despair of asking what the best mobs are for making spectres and zombies.
Best of Luck!!