An exploit or not?

when we do creep stacking and lets say after 3 stacks, killing the stacked creeps in smoke of deceipt with an aoe spell, is an exploit or we can do it safely?

thanks for help!

Until valve decides whether or not it needs to be changed, it is viable and safe to do.

To add to this, it's fully counterable by invasions as well; once you close the distance to him, the Smoke'd hero will appear inside his massive stack and most likely die horribly, leaving you free to clean up the creeps. 5+ mins is a good time to invade against Smoke of Deceit junglers, particularly otherwise worthless ones such as Storm Spirit and Io. Getting an Observer Ward up to keep a close on the stack is another option as well.