A Site of Power is a type of mini-dungeon in Nightingale, and completing it rewards you with the schematic for a Major Realm Card. The first one you'll likely come across is the Antiquarian Site of Power, and completing it is required for an early quest. 

Sites of Power are usually easy to spot as they are generally large structures, though their appearance will vary, depending on the biome. The entrance is sometimes high up so don't worry if you don't find it right away, and be aware that you may need to raise your gear score before it will let you inside. With all that in mind, here's what to expect when you venture into your first Site of Power.

How to unlock a Site of Power 

When you first stumble across a Site of Power, whether that's while wandering around looking for resources, or following the quest that directs you to one, you'll likely find the entrance blocked by a magic barrier. Presumably this is for your own protection as you need to equip better gear before you can go inside.

What's really handy is that you'll get a quest for any Site of Power you venture near, and this will show you the gear score you need to reach in order to get inside, just to the right of the quest text. You also won't need to worry about finding your way back to it if you need to work on your equipment as it will show up on your map automatically from that point on. 

Nightingale Site of Power: What to expect 

Each Site of Power is different but you can expect to encounter groups of enemies, or occasionally, puzzles to solve. It's also worthwhile keeping an eye out for chests which contain random but potentially useful items. You'll also need to defeat a boss at the end, so bring along enough resources to make a bedroll, as well as enough food to tide you over.

If you're playing solo, bringing along a companion won't hurt either. While they're not amazing at fighting, having someone with the ability to revive you if you go down, not to mention take the heat off you by distracting enemies, is never a bad thing.

While most are fairly easy to deal with one-on-one, you can quickly become overwhelmed if too many enemies rush you, which is likely to happen in a Site of Power. I have been lucky to avoid entire groups by remaining unnoticed as I've descended to lower floors but when you do have to stop and fight, it's not a bad strategy to try to separate them and draw a few at a time up a flight of stairs or around a corner.

You need to interact with the console in the final room to summon the boss, but before you do so, check that you are rested and ready to go before initiating the fight. Most bosses have some sort of weakness, whether that's an actual weak spot on their bodies or less resistance to a particular damage type, so take a moment or two to figure out what that is at the start of the fight, rather than expending your energy needlessly.

Once the boss has been taken care of, interact with the glowing console in the middle of the room to receive the Realm Card schematic and complete the associated quest.