Toz had slowed down slightly after the Rat King crashed into the ground in order to keep it right on his tail and make sure it steps into all the traps he leads it through. Since the Rat King might try and take shortcuts if the distance between them is too great and thus avoid one or more traps, Toz wanted the Rat King to not even have to think about finding a way to close the distance quicker.
Thankfully the Rat King was so caught up in chasing Toz that it didn't even think of trying to avoid the traps, especially when it couldn't even sense them until after they had been triggered. The Rat King couldn't understand how there were absolutely no mana fluctuations from the traps until after it had already been caught by them. Despite the attractions and devices clearly containing mana, there were no signs of them while they were still hidden underground.
