Camp DeBenneville Pines. I forget if I was a camper or a councilor, but I heard "Mical The Dragon's Daughter" for the first time and was rapt. The whole camp was enthralled - and this was one of those chilly DeBeneville nights - we loved the butterfly cape and the growing potion (and the later addition of the flaming sword. I was enraptured by the twist and have never forgotten the story.
He lead workshops that always resulted in the campers creating amazing stories. It was watching the products of one of his workshops that I met one of my best friends. I was a first year councilor and she was an aging out camper (and an angry gnome) it was magical and awesome.
He, Billy and Corky led us into the labyrinth one night and we all ended up doing a rhythmic dance thing in the center. Totally spontaneous.
I have a picture of Mark where he totally has pointy elf ears (no prosthetics!). I swear he was actual magic.