Monsterling (2 in 1)

What was the benefit? 

It would be the little boost in power that he gained from the risk of swallowing the crystal. Tang Ling realized it when he jogged for several steps. He discerned that he was faster, hence his change in expression.

However, the feeling was subtle. Back when he was in the situation, Tang Ling could not verify it and had no idea how much stronger had he become.

Therefore, he wanted to return to the Hope Barrier as quickly as possible to verify his speculation, and then use his Precise Instinct to provide the most accurate answer.

He was excited as he thought about it. It seemed like Worf's absurdly stalwart abilities invoked his admiration towards power once more.

To Tang Ling, he did not fear others being stronger than him, but he was afraid that he would reach the end of his power-seeking quest easily.