YOU COULD THEORETICALLY JUST SHOOT THE WINTER QUEEN WITH A HIGH-POWERED RIFLE BUT GOD HELP YOUR PITIFUL SOUL IF YOU ACTUALLY TRY
WITH ALL THIS TALK OF MAGIC SHIT YALL FORGET THAT NORMAL MUNDANE VIOLENCE STILL EXISTS I DON'T ENTER FAIRYLAND UNLESS IM STRAPPED
"I don't enter fairyland unless I'm strapped" is basically a declaration of godhood.
the fastest way would be to make bullets out of cold iron instead of lead. Even if they manage to get the bullet out, it would already have depowered them