1000 Point SDI!
When Dante emerged from the pocket dimension suddenly, you could be sure that the spiderlings that were attacking it were shocked, much less the spider warriors or the single Spider Lord.
They only had time to screech in anger when Dante unleashed a wave of hellfire that engulfed the very small army before him. After all, he had already dealt with the majority of the forces at the bottom and these were just the reserves who weren't there at the time.
In a single attack, pretty much all the spiderlings were taken out, with a few spider warriors following along. The rest quickly retreated rather than advanced at the command of the Spider Lord, creating a defensive formation as they watched Dante warily.