Every floor you travel through, from the first floor to the last floor, has a chance to spawn one of the dark purple Cthulhu shrines that you can pray at. It gives you choices of healing yourself, recharging wands (I think), and increasing cum storage.
If you have never encountered even 1 of those shrines, over multiple games (or loops), you either have the shittiest luck with this game or RNG just hates your frigging guts.
When you use one of the Mapping scrolls and there is a Cthulhu shrine, it will show up as a purple C on the map.