For a russian tortoise?? which bulb??

don't go above a 100w for an indoor enclosure, i have a repti glo bulb 10.0 this is plenty if you are going for a 100w one you need to fit it with a thermostat as they get really hot and can go above the recommended temp making the tortoise too hot, ideally it is better to have a heat lamp and a good UV lamp that does not get too hot, they do kick out a lot of heat so you have to be careful, best of luck with your tortoise honey