While Lord Maranos could drop any number of random rewards Diablo 4 Gold, the thing that you're interested in is the one he's guaranteed to drop an Sigil of Zakarum. Why is that drop so vital? The reason is that they help make the fight in the fight against Ancient Nightmare just a touch less difficult.
It's the first time you know this: the Ancient Nightmare can only be found every Wednesday and Friday at 12pm 3:00 pm, 8:30 pm, and at 10 pm (local local server time). If you're looking for the boss any other time, you'll be sorely disappointed by what you don't find.
If playing Diablo Immortal at the right date and time But, make sure you head towards the Misty Valley area of Mount Zavain. The Ancient Nightmare guards the area surrounding the Misty Valley Waypoint. If you're in the area, you should receive an alert that indicates it's been summoned by the boss and you'll be able to automatically navigate to it. Furthermore, the boss appears to be an enormous, Xenomorph-like being that is surrounded by a glowing shield. It's hard to miss.
The fight for victory against Ancient Nightmare is a little difficult. The battle requires you remove the Ancient Nightmare's shield in order that you're able to begin damage to him. While the attacks of the Ancient Nightmare seem to be fairly simple but it's going take you a long time to dismantle that shield and start chipping away at its health MMOexp Diablo 4. It's easy to conclude the whole thing is impossible.