If those two bite you at the same time, you're pretty much [censored].
Seriously though.
If you are aiming at some sort of hybrid or something, I think that it would be bad idea since it would have to be something uber strong and everyone would try to become it.
It's best not to mix them.
If you are not aiming at that and you're just wondering how it should work out, then I think that it should be made that it's impossible to get both at the same time.
Even though, I'll vote for version where it kills you since I think that would be the coolest option.