And what's the druid grove one?
It's a fully-explored subdungeon with a druid sitting in the middle. If you talk to him, he gives you three options:
1) Pay me 5 gold
2) Pay me 20 gold
3) Pay me 35 gold
If you choose the 5 gold option, you are given the effect of IMAWAL and your next kill grants +50% XP. If you choose the 20 gold option, you gain a Tikki's Edge effect and every kill grants +1 XP. If you choose the 35 gold option, you are instantly granted level-up complete with full heal. Once you've chosen an effect, you cannot purchase a different one.
It's a potentially game-changing subdungeon that ranges from absolutely horrible to kick-ass depending on your needs. Since it's fully-explored, you get zero regeneration which is a killer in the best of circumstances. The low-cost option is largely worthless and inferior to the paltry 15 tiles you get from ying/yang, but the two higher pay-scale items can turn an entire dungeon run around.