A Mighty Wind Cave
At the back of the cavern you find a crystalline paradise, a palatial room filled with crystal struts bigger than yourself. Many of the bars have a faint green glow, to which your talisman seems to react by beginning to glow the same color. Weird.
From the back of the cave, through a series of holes scattered like morse code amongst the crystals, a mighty wind begins to blow. Unlike the cool, dank air in the rest of the cave, this wind is warm, invigorating. The wind seems to pick up the glow from the crystals, and as it passes you, the light appears to swirl into your talisman.
After a minute the wind subsides. The glow is gone from the rocks, your talisman has returned to normal, but you feel mightier than before. You gain 10 strength.