The contents of Issue 16 have been revealed in an announcement on the official City of Heroes website.

Issue 16: Power Spectrum  focuses on power customization, and in it players will be able to customize each power individually with different colors. So, for example, Fire Blast can be blue, while Fire Ball could be pink, all in the same power set.

Also, so the melee sets like Martial Arts and Super Strength aren't left out, they will be receiving an alternate animation for every power in their set. Unfortunately, sets like Necromancy and Stone Armor will receive limited customization options, though no specific details on how limited they will be are available.

There will be some more proliferated power sets included in Issue 16 as well:

Powerset Proliferation - More powersets are now in the hands of Archetypes who couldn't use them previously! Blasters will have access to Radiation Blast, Brutes will get their Claws on, Controllers can now freeze it up with Cold Domination, and Corruptors get to feel the "twang" of Archery and Trick Arrow. Defenders can go high-tech with Assault Rifle and Traps, and Dominators can pulverize their enemies with Earth Assault. Masterminds heat things up with Thermal Radiation, Scrappers and Tankers get ready to fry their foes with Electric Melee and Electric Armor, and finally Stalkers get to swing their own mighty Broadsword.

Some other notable features of Issue 16 include the ability to adjust mission difficulty to your own specifications. If you've ever wanted to see if you could handle a mission set for 8 (while solo) and have all the mobs spawned four levels higher than you, you'll be able to do just that!

For more information on City of Heroes Issue 16: Power Spectrum check out the full overview here!