While large echoing cavernous chambers seldom are the first pick for a good acoustic space, Delay effects have been ubiquitous in sound processing for a long time.
The kHs Delay can be run both free running and tempo synced with various stereo and feedback options. Most notable however is the duck feature, which optionally only lets the echoed sound through when there is no dry input signal. This allows for long and heavy delay while still avoiding clutter over the original sound. Clever!