Let me guide you through reaching that late-game area without doing the quest everyone talks about. You'll need to push through until you've dealt with morgott and gotten access to the mountaintops first, since this is definitely the longer route. Start by tracking down both pieces of the secret medallion - the right half is with albus, who's hiding near the village of the albinaurics in liurnia, and the left half waits behind commander niall at castle sol's peak.

Once you've got both pieces, head back to the grand lift of rold and switch your action to use the secret medallion instead of the regular one. This opens up the consecrated snowfield, and from there you'll want to push northwest past the yelough anix ruins. Keep an eye out for a sanguine noble invasion - take them down and they'll reveal your ticket in: a blood-covered teleporter that shoots you straight to the palace.

Tip: this whole route needs you to be pretty well-leveled, especially for commander niall, but it's worth it if you're looking to avoid the invasion questline. The palace itself is no joke though, so make sure you're ready for what's waiting inside.