GosuGamers is proud to present a series of guides on heroes. Each guide would be in-depth and comprehensive for easy understanding. So without further ado, follow the link to find out more about Io.
Short quote from the guide, Dissecting Io, the Guardian Wisp:
No matter what you aim for – safe pushing, ganging, pressuring lanes, turning a battle from 3 on 3 to 5(4) on 3 – Wisp is probably the most versatile and useful hero in the current DotA version.
Links
Dissecting Io, the Guardian Wisp - Full guide