In legend, antagonists/monsters/loot-on-legs are made the exact same way as PC's, though less restricted.
I have always loved hordes in epic fantasy, but the rules make this hard to portray at lower levels, since a monster is at least Level 1, and therefore an encounter with it is at least Encounter Level 1.
How do you make an Encounter of level 1, featuring multiple enemies? The classic goblin swarm, for example. I know that I can house rule to my hearts content, obviously, but I would rather see something that is actually playtested, preferably also from official sources.