Conditions for buy signal are:
►Crossover out of Shaff Trend Cycle's extreme levels
►The price is above its short period .
►A short period is above a long period .
*Conditions for sell are the opposite.
All in all, I don't think it needs to be on your chart but it can be optimized and even successful on some timeframes.
Shaff Trend Cycle solution was provided by @everget, I converted his script to Pine v.4, added exponential averages and created an algorithm for backtesting.