Mine would be the PICK me Spell.......
In this spell it would make my chances of winning anything better... Ok it would let me win the prize i want to win:) before you enter the contest or drawing you will take your wand tap the entry three times. Then take my wand and move it in a triangle shape over it while saying nickel nickel pickle tickle a winner pick a nickel for me. depending on where in the contest you want to come in at you say it that many times:) then find a muggle to give it a kiss. Then its a sure fire you will win! so i look forward to see you at the preview of Harry Potter and The Half Blood Prince:)