re the dervishes challenge game.
I'm intrigued by the fact that shrive was classed as 'rare' yet managed to garner considerably more hits than its modern (but, I suspect, seldom used) preterite / past participle form shrived which was classed as 'common'! (144/86)
What about the older forms of this rather archaic verb - shrove and (un)shriven? Are they common?
Shrovetide and Shrove Tuesday (known in UK as 'Pancake Tuesday' and in other parts of the world as Mardi Gras) are normally written with capitals, so that might exclude them.