If he sees players in their human form outside of the cell or within one space of the cell wall, he will deal some damage (normally around 100 life points, but potentially up to 200), and send them back in. It is interesting to note that when in gorilla form, you could block him, so he would 'teleport' around you. This could be useful for questers who wish to save time and food by simply waiting for the guard to go north of the player in monkey form and quickly follow the player so the guard would 'teleport' around, running through the player and avoiding being jailed again.