Skills represent your character's abilities outside their Powers.
At character creation, you have 4 points to spend on Skills, plus an additional 8 points which may be spent on either Skills or Powers. All Skills start at level 0, and go up to a maximum level of 5, however 3 is the highest level available at character creation. During Advancement, it costs 2 points to increase a Skill to level 5.
It should be noted that while it is not necessary to have Skills that synergise well with your Powers, taking ones that do will allow you to make the best use of them. For instance taking Combat if you have super-strength will not only allow you to hit things really hard, but also know where you should aim to do the most damage.
Combat represents your fighting ability. This can range from hand-to-hand, to swords to firearms. Feel free to specify how your character fights when you generate them. It also represents your ability to avoid harm in combat situations, and general agility. Note that this skill is required to be effective in a fight. Even if you are capable of causing great harm using your powers, it will be hard to use them in a combat situation without this skill.
Expression represents your ability to express yourself and affect the views of others. This can take many forms. It could be through their social skills, inspiring speeches, or even great works of literature, art or music. Note that to maintain player agency, this skill does not work on PCs - you will have to rely on your OOC ability to persuade them during session and in emails. It is also harder to persuade NPCs who are particularly well versed in this skill, although it is still possible.
Investigation represents your ability to gather information about a person, place or thing, and, where appropriate, use that information to make deductions about events that have happened while you were not present. This might also include a degree of academic knowledge.
SCIENCE! represents your knowledge of the laws of nature and your ability to push them to their limits, as well as create technological devices and other academic knowledge. Note that what you can create with this skill is limited by the resources you have available. Biological and chemical experiments require the proper lab equipment, while feats of engineering require the raw materials. Additionally any items created that are similar to super-powers will be of limited use unless the appropriate power is taken to use it.
Stealth is your ability to move about unnoticed by way of disguise or concealment. It also represents your ability to sneak up on others, steal things and hide objects.
Strategy represents your ability to think ahead and coordinate groups of people, be it in battle or organising large events. It also helps you to react to others' plans, or adjust your own should they go awry. Note this skill will need to be used to command minions and such in a fight effectively.