Why did Snape had to kill Dumbledore?
So, dumbledore’s plan was to have Snape kill him, since he was dying anyway, cementing Snape’s position with Voldemort and making him a more effective spy.
How did Snape feel about killing Dumbledore?
Why Snape’s Avada Kedavra Was BLUE When He Killed Dumbledore – Time: 1:084:10 –