Pit firing is a technique for firing pottery where the pieces are wrapped in flammable objects and literally put in a pit to fire. The flammable objects burn off in different colors, which gives the pottery a very unique appearance. Foil saggar is when you wrap your piece in foil to contain the gases and smoke that result from the chemical reactions.
Though I don't have any planning process for my pit fire peace (I just sorta messed with the clay and stuff happened), I do have a picture of my piece in progress after coming out of the bisque kiln.