The ancient weapon

The moment the elites dipped their feet inside the water , they noticed their stamina bars depleting very quickly however their exp bars rising equally fast. 

If one played their cards right and kept refilling their stamina bars by drinking potions , they could potentially level up within minutes inside the mysterious water. 

Rudra took full advantage of this opportunity , as he kept drinking stamina potions to supplement his stamina bar , while his exp bar kept rising.

However he clearly noticed that with every subsequent level up , the effects of the water reduced , as the stamina burn up rate was lower and so was the the exp increase rate. 

5 elites lined up as they had their legs dipped inside a massive indoor pool of water , as they chugged stamina potions and talked about life untill a few hours later everyone had levelled up about 8 times with Rudra levelling up five times.