Wouldn't it make sense to put level correct villain groups in missions so that a hero does not have to face +7 villain groups? The Obtain Cupid's Arrow is a very good example of this! I also think the villains in the sewer should be zone specific levels like the surface cities they are under, that would make sense....leveling up to 9 or 10 by the center of the sewer system means you will still encounter level 3-5 characters under Skyway, Steel Canyon, Boomtown, Kings Row, where higher level villain groups are.