Leech projects a dampening field out from his body that disables any additional neural pathways found in the human brain, temporarily blocking access to any paranormal abilities (including other mutants, extraterrestrial, magical, etc.) so long as he's within range of his field's variable radius, which is approximately ten yards. Some physical effects, such as being thin, may also occur depeneing on the nature of the powers that he negated.
Martha Johansson (No-Girl)Edit
Martha is able to negate or block the use of others' mutant powers. This power is much like the Morlock Leech's, but, unlike Leech, Martha has conscious control of her powers. The range and upper limits of this ability are undetermined.