Mission Selector Screen:
The potential this gives is insane, this is only the test server and there are thousands of missions out there for you to try. Endless custom content is really the name of the game, with each account able to have 3 published missions at any time, the number of potential missions is staggering.
Mission Parameter Screen:
This is really just the tip of the iceberg, the broadest look at what you can make. Each group has its own options, ranging from location, to size, to how they react when low on health (calling back up, running, ect)
Custom Enemy Parameters:
You can make a custom enemy for each enemy rank, each with thier own toughness, power choices, and abilities, allowing for whatever you want.
Custom Enemy Power Selection Screen:
This lets you pick from any power set that is available to players in the entire game, depending on the difficulty you set on the previous screen, determines what power from them sets are available to the enemy. Basic only gives the first few powers, while Extreme will give them everything, including the Tier9 (Alpha powers, nukes, super shields, strongest attacks, self rezzes, ect)