makeing a unitype have an attack of 0 damage (but still have an attack)

yeah i need a way to have a unit attack a unit and do no damage, with out going into negative by any chance and it has to be exactly 0 damage. some one plz help me out since i set the base damage to 0 and 1 die with 1 slide, but he still does 1 damage

i hate to bump but i seriously need an answer

Set the base to -1 and the sides and dice to 1 and the attack will be zero, and no you can make its attack do 0 damage unless you use negitives and all the other way would be more of an effert then just making the damage base -1

Finnaly An Answer Thank You Sneb!