You could use a heat lamp for a little while, but it will make it fairly hard to maintain humidity. As well, you will need a temperature gun to make sure the spot under the light is about 92-94 degrees. It would probably just be easier to get an under the tank heat mat and a thermostat. Also, I would only use a red or black heat bulb as white light will irritate ball pythons as they are nocturnal. Ceramic heat emitters are hard to use if you are trying to make a heated spot of that temperature.