Title says it all. Just got destroyed by a 5x Blademail + 1x Blink Dagger Legion Commander. Hilarious really because any damage whatsoever that you deal gets dealt back 5x to you. As a Shadow Shaman I instagibbed myself by shackling Legion Commander while someone else was dueled.

Apparently you don't have to click all 5x, just click 1x of the Blademails and they all take effect.

Blademail is not supposed to stack as far as I'm aware? Though you could have some fun as a Pudge or as Centaur...