I'd recommend against doing that, at least so blatantly. Being able to shrug off the Killing Curse is one of the most obvious signs of Mary-Sue-dom in HP fics, to the point where most don't do it (at least in the fics I read), or it is a major plot point. Besides that, the Killing Curse is unblockable, barring the involvement of old magic, Aslan at the Stone Table level stuff.
In any case though, it probably wouldn't come up, as, IIRC, the only wizard that uses the Killing Curse in combat in canon is Voldemort. That "roomful of flashing green light" just wouldn't happen. Instead, Doug would be up against a veritable rainbow of rays, capable of combining to create bizarre, unexpected effects.
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Stand between the Silver Crystal and the Golden Sea.
"Youngsters these days just have no appreciation for the magnificence of the legendary cucumber." --Krityan Elder, Tales of Vesperia.
In any case though, it probably wouldn't come up, as, IIRC, the only wizard that uses the Killing Curse in combat in canon is Voldemort. That "roomful of flashing green light" just wouldn't happen. Instead, Doug would be up against a veritable rainbow of rays, capable of combining to create bizarre, unexpected effects.
-----
Stand between the Silver Crystal and the Golden Sea.
"Youngsters these days just have no appreciation for the magnificence of the legendary cucumber." --Krityan Elder, Tales of Vesperia.