Rogue - Killing Spree

[Relina]

Killing Spree is currently bugged it does -20% damage instead of +20% damage while its active

Patch 3.1.0 (2009-04-14): Now also increases all damage done by the rogue while active by 20%.

[Rehan]

It also removes combat after every jump, so if the rogue is fast enough he can stealth right after he used Killing Spree.
Not sure if that is how it's supposed to work or it's bugged.

[Folkk]

Damn, so many negative rogue bugs

[ItchyVortex]

They also have gamebreaking "positive" bugs, but you only abuse them if you want