What does Blight Serum do on certain killers?

"This add-on may have unknown effects on certain Killers"
So what are these unknown effects on what killers? I know on Blight it just gives you 6 rush tokens instead of 5 but I can't imagine what kind of unknown effect it could have on any other killer.
Comments
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Blight gets an extra Rush-Token. Thats it.
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Unknown effects mean bugs, that's it.
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Every other kills gets a single Rush at the start and everytime they hook a survivor. But the rush takes priority over any killer power. so be aware of that. E.g. you frist use your rush before you can playce a trap with Trapper. And so on ...
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Yeah ik how it works normally, was just wondering about the "unknown effects" part of it
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Yes its really sucky, only good for memes and maybe on blight.. can also only be used during the Halloween event unless they change it this year. Which is annoying since the survivor side can use their event stuff all year..
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I think that are the whole "unknown" effects, one extra rush token for blight and singular rushes for everyone else.
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