Title says all. Here comes another exploit found in the Dota 6.67c just short after the Roshan Bug. This time you can have permanent Windrunner's ultimate (Focus Fire) with no Damage Reduction. It's kinda game breaking bug and may cause rage quit of your opponents but you may try it for fun :)
How to abuse Alleria - Windrunner Focus Fire bug:
• Windrunner, Level 6 with Focus Fire.
• Darkseer with Ion Shell.
• Cast Alleria Ultimate on a hostile and cancel it (don't hit the unit).
• Use Darkseer to kill that unit with his Ion Shell.
• Now, Let Windrunner to attack units with her own. Don't use attack command.
• Tadaaa, Y0u've got permanent Focus fire on Windrunner, it is a permanent buff it won't go even if you die. Perfect!
Maybe, now IceFrog might release DotA 6.67d or Dota 6.68 to fix all these annoying bugs. By the way, visit DotA-Utilities.com for all the latest updates ;)
Credits to Andreacirri and Kuarinofu