Dark Souls has become more accessible over the years, but if you're new, some parts may still seem like a mystery. It's not spelled out how you're supposed to play with friends, for example. I'm here to break it down. There are two ways to play Dark Souls: offline and online. If you play online, it's possible for other players to invade your game and kill you. But you also get access to the incredibly useful messages on the ground left by your fellow adventurers, stuff that can warn of ambushes and secrets.
As you might expect, playing online is the only way to connect with strangers, whether you want to play with them or try and fend them off.
For reference, Dark Souls calls joining multiplayer games "summoning".
Asking For Help From Strangers
This can technically happen anywhere in the world, but you can't just randomly matchmake with someone; you have to find a summon sign that's been placed in the world by another player. They look like this:
This is a screen shot from Dark Souls 2, but it looks this way in Dark Souls 3, too.
First, you need an ember. You know how your character lights on fire after beating a boss? Same idea. You can trigger the this using an ember item. Embers are available for purchase in limited quantities from NPC vendors, hidden in the world or earned by helping other players defeat bosses.
You're going to find most summon signs outside the door to a boss; that's where most people have trouble in Dark Souls. If you don't see any, it's possible that no one is offering assistance, or there might be some rotten luck with your connection. Sometimes it's useful to leave the area and come back, and see if the game's able to pull in a fresh batch of summon signs.
When someone joins you, there's no friendly fire, so swing away in battle. But the moment you beat a boss, they will be dismissed from your world, and if you want to play with someone else, you'll have to summon again.
Asking For Help From Multiple (!!) Strangers
By using an item called the Dried Finger, it's possible to bend the rules of Dark Souls and have more than one person join your game. For every new person you summon, though, the game introduces the opportunity for a malicious player to invade. Asking for help doesn't come without its risks.
"Use with caution," indeed.
If You Want To Help Other Players
Being summoned into another person's game and helping out is one of the most rewarding things you can do as a Dark Souls player. It's addicting.
To do this, you'll need to the White Sign Soapstone from the Shrine Handmaid NPC in Firelink Shrine. (The lady who wants ashes.) It's only 500 souls, and you can use the White Sign Soapstone unlimited times.
You do not need to use an ember in order to help other players. In fact, when you're summoned into a game, Dark Souls will reduce your health and Estus Flask count, to make sure you're not completely overpowered. (An ember actually grants your character more health than usual.)
Since players have to specifically summon you, it can take some time. I recommend laying on the ground and catching some sleep while you wait.
How To Play With A Friend
In the past, the Souls games didn't let you choose who to play with. That changed in last year's Bloodborne, which introduced a password system. Fortunately, From Software has brought the same system to Dark Souls 3.
Before you lay down a summon sign, you can attach a password to it:
If the other person punches in the same password, the game matches you.