The shift was far from subtle. The eleven immortals had been working together to resist Lex's assault, keeping him from doing any significant damage. Their strategy, while defense oriented, was not bad.
They did not need to harm Lex themselves. After all, they'd already learnt that if they took out overpowered treasures, so could he. So instead of pushing him, they were just holding him at bay, and letting the tribulation do the damage.
The tribulation was already at the level where Lex could no longer simply ignore it. The energy within the lightning bolts could nourish Lex, evolving his body further, but the laws within were purely harmful.
The plan was sound, but it could no longer work. Not only was Lex acclimatizing to his new realm a lot faster than any of them anticipated, he had enough brute power to kill them.
