Her instincts had been enough to kill Slayers. Well, newbie Slayers with minimal experience. And she'd taken out many a skilled vampire. But not exactly one of Spike's level in a while. She was cocky and it made her forget the number one lesson. Don't forget he could get lucky.
She managed to dodge the hit aimed for her face, but didn't see Spike's other hand moving until it was too late and the stake was embedded in her heart.
This isn't how it's meant to happen
She looked down with shock before glaring at Spike.
"Bitch."
She crumbled into dust, glaring until there was nothing left.