When a void spell echoes due to the VK mastery bonus (including echoing strikes, time legion, and avatar of regret) it always procs a devouring orb. My expectation was that the spell you cast would be echoed.
I first noticed this with abyssal echoes causing devouring orbs to be created. Turns out it also works when toggling ravaging or ephemeral stance since they are ‘void’ and ‘spells’. Here’s an example: