It seems that whenever I use E-Surge/Burn/Weariness, it always shows -8 energy, even when they dont have that much. Burn/Surge will do 50 damage, or 30 damage, or whatever, but it always says -8 energy.
You can't deny into negative energy. For some reason, it just says '-(x)' even if they loose only 2 energy and are then back to 0. The only way to tell exactly how much they lost is by the damage.
Or by when mind wrack is triggered. I agree it is sort of annoying, but I think it is just meant to make playing an e-denail mesmer more difficult, not a bug.