Marlene/Sirius
Everyone else had opted for disillusionment charms, but not them. Sirius had an invisibility cloak that allowed him to stay close to her and she was partying. Her hair was dyed red with blond streaks. Her robe was downright modest for her, but she was still giving a perfect view of her boobs through the sheer fabric that covered her décolletée. Even though she had cast plenty of charms and applied make up, she found that the lace distracted men better than any glamour.
She always found that the best way to hide was in plain view, which is how she found herself flirting with the Head of Department of Magical Transportation when James message arrived. She couldn't waste such a beautiful opportunity to kill Augustus Rookwood.
Marlene giggled as some inane joke he was making, before leaning closer. "Let me tell you a secret," she whispered in his ear, and he leaned closer, his arm brushing against her breasts, proving that men really were idiots. "Avada Kedavra." She said it softly, but it ddn't matter. She held him up, before starting screaming and pointing in the opposite direction, yelling nonsense. As the crowd began to look around, she slipped away, winking at Sirius as she passed him by.