Wait why did both of them drenched?? Did leila planned then backfired or what??

I think because she was trying to crush her hand while she responded with fire

Leila planned on dosing water on Las (think she did this when they first met too) but Las knew figure that out and pulled Leila's hand so she'd be doused in water too

Py attention to Leila hands in that scene

Yes indeed so probably both