You said yourself, heroes can deal damage to gain energy - so spec should never not gain energy. The only possible way a spec should timeout against a line is if he didn't have time to possess, then wait for each enemy to die, or if he was up against Bone Dragon.
I should note that Bone should not drain spec aside from the initial drain of the match, since all of her damage is physical except for the orange skill damage done at the beginning of the match.
I've asked this to be looked into, but... at least they fixed the issue with Free Rune Removal events not displaying properly! That will come in handy every few months when it results in a handful of players not being confused for a couple seconds. /s