Not again
Unlike the previous tests, where Lex won after exchanging just a few moves, this one took him a little over an hour. The deep-sea creatures, still in the Golden core level, seemed to have a very strong resistance to lightning. The only reason they took any damage at all was due to the tribulation attribute attached to those specific lightning bolts.
It was a trap which took advantage of his assumption that lightning would naturally work well against creatures in water. It was only after Lex had this realization and changed his form of attack that he made some significant progress.
All Lex needed to do was rely on his left eye to check their weaknesses. If he had done that from the start, he would have avoided wasting time, but he had not since he had made an assumption.