The Collector immediately noticed a shift in its senses. It had an unnatural connection to this twin mountain range in the first place, capable of sensing its heart through a psionic tether like that it possessed from the goblin lord's dungeon.
This meant that the Collector knew the shortest possible path towards the heart, but if the shortest path changed, then the tether would update positional information accordingly. It did so now. The Collector sensed that to enter the portal at the end of the hallway would lead near directly to the heart of the mountains.
The portal beforehand had been a proxy. A much longer, much more roundabout path that likely would have even led to dead ends.