The "Hard" Clusters are mostly built for seconds, Hard are called because their sound is very hard.
To be more dissonant, due to the number of second, they were used by composers like Ligue, among many others, and in the Jazz by the great pianist Paul Bley, the innovative artists like Cecil Taylor associated with the Free Jazz. On the guitar they can be heard in the brilliant Allan Holdsworth, among others. It can develop on all scales and shades.
It is advisable to raise the fretboard and lower the thumb, for a more comfortable technique, since the clusters want to open the left hand a lot.