Vorthas could withstand the infinite deathly essence of the Beast, but not for long, but he had held on long enough for the Primordials to finally guage the power that the Beast had to offer, although they knew that this was far from the limit of Death, it was enough for them to push through, and behind Vorthas, the six Primordials suddenly split apart, and they began attacking.
Although this opening salvo between Death and the Primordials seemed to have taken a relatively short time, that was only because the perception of these entities was far too powerful. It should be noted that the regions of Death were so broad that it would take an immortal trillions of years to cross it at a straight line travelling many times the speed of light, not to mention exploring more of its depths.
Except for attacks at the Primordial level, any other lesser dimensional attacks would take forever to even cross a single region of Death.
