"Oh, bad luck, Harry."

[Caius Marcius]

--- In the_old_crowd at yahoogroups.com, Barry Arrowsmith 
<arrowsmithbt at ...> is like:
> 
> See, I got to thinking. If there's the Felix Felicis Potion, why not  
> the exact opposite, an Infaustus Infusion. Have a slurp of that  
> and ... oh dear.

No need to for extra-Canonic invention here - adhering to Canon will 
allow the same results. See FB&WTFT - specifically, the Mackled 
Malaclaw: "The Malaclaw's bite has the unusual side effect of making 
the victim highly unlucky for a period of up to a week after the 
injury.  If you are bitten by a Malaclaw, all bets, wagers and 
speculative ventures should be cancelled, as they are sure to go 
against the victim" (p. 28).

    - CMC