1.0 is 100% (no change), not +100%. It's a multiplier. 2.0 would be 2x (+100%). 0.8 would be 0.8x; 80% of the original damage value, which is 20% less than 100%, so -20% damage done.
You can give penalties with bonuses, and vice versa, but...it doesn't look good when inspecting.
Linear Mode
