Forum:Difference between Damage and Paying a Cost?

I was wondering if I had both "Krebons" and "Des Wombat" face-up on the field, does the cost of using Krebon's effect reduce to 0 because of the effect of Des Wombat? I was thinking mostly not because Des Wombat reduces damage and not paying the cost of a card effect, but is there really a difference? I would really like to know. If they can go together that would be great!