Bat guano is rich in Nitrogen [N], Phosphrous [P] and Potassium [K].
Mix within your substrate or sprinkle over the top of a pre setup terrarium to give a boost of nutrients to your plants and soil.
 
Detritivores such as isopods and millipedes will eat some of this within the substrate and it will speed up the decomposition of organic materials.
It is also said to have Anti-Fungal properties too.