Question about backstab in assassination spec. "murderous intent" level 2 can let the backstab refund 30 energy under a certain condition. let's say without considering the glyph bonus, the backstab will cost 60 energy. With the talent "murderous intent" level 2, I presume the backstab still require rogues to have at least 60 energy to use the ability then return 30 energy. Or rogues actually can use backstab when they only have 30 energy? Thanks, just curious.