What if you used mass hydra and always had a nydus worm. Once you engage you drop a nydus behind your army as an exit strategy.
Been done pretty often, the nidus is expensive, but make sure you have something to tank for the hydra, they're made of tissue paper.
Because when Hydras get countered they die so fast your nydus won't have time to complete.
I one time massed hydra even when i knew he was going colo, I wanted to see what happened when we engaged. Lol.....................