Volume Impact (The area)
Average Volume (The thick line, xTrigger)
Volume Impact = Volume Chance - Average Volume
It provides very reliable buy sell signals. Buy(green) when increasing, sell(red) when decreasing. Volume Impact might drop before the actual price so it has an early warning potential.
Before trend changes volume average diverges from the prices. It moves reverse to the prices.
Also before trend changes, volume impact peaks diverges from price peaks. So you know a big drop is coming.
In summary, you can foresee trend changes.