How hot is too hot? I like the masa idea. I often will boil corn tortillas in beer, with freshly ground anchos, until the tortillas dissolve into a thick "mush" which I then use to thicken and flavor my chili with. Never thought of using it to tone down a chili but it would work. If it isn't too, too spicy then serve it as is and offer up plenty of sour cream and wedges of lime for people to finish their chili with. Both the dairy and the acid from the lime will help take the edge off of the chili for those who don't like it too hot.