Hey guys!

I am running DoIP for a four players. A rogue assassin, a tempest cleric, an oath of devotion paladin and draconic sorcerer. They're currently at level 4.

They have decided to venture to the Dragon Barrow and retriever the Dragon Slayer. Since the adventure books stated that it's completable by level 4 characters, but is balanced for level 5, I've warned them through NPCs that the place could be very dangerous, but I didn't break their determination completely, although I think I managed to make them more cautious.

Now, is this dungeon really doable by their party? I've checked, and the Encounter Builder states the Invisible Stalker alone would be a deadly encounter for them.