PSA: You don't need servant coffins to upgrade your castle heart in V Rising
So, you're playing V Rising for the first time. You've got yourself the foundation of a nice little vampiric castle on the go; plenty of crafting stations, resource refineries, and maybe even a little crypt where your coffin is securely stowed. The problem is you're struggling to upgrade your castle heart through the main tutorial questline.
The Expanding Domain quest tasks you with levelling up your castle heart from one to two, but when you look at the heart, it seems to require four servant coffins and 50 floor tiles. You have no servant coffins and even if you browse through the list of V Blood bosses and their unlocks, none of them seem to drop the schematic either.
The good news is that you don't need servant coffins to upgrade your castle heart—it's just a confusing interface. If you hover your cursor over the "upgrade castle heart" button, you'll see that it instead costs:
Twelve copper ingots
Twelve leather
The four servant coffins and 50 floor tiles are actually the cap for your current castle level, meaning you can have four servant coffins active and that much space in tile terms. It's a very confusing visual layout, and the funniest thing is that I was confused by exactly the same thing when I first played the game two years ago in early access.
In terms of servant coffins, as you progress through the main tutorial, you'll get a quest to build a stone coffin, which will then reward you with the servant coffin schematic. The trickiest part of crafting one of these is acquiring greater blood essence. You can make this in the blood press using four unsullied hearts, but since these are a rarer drop from high-level human enemies and V Blood bosses, it takes a little while to gather them.
When you do wrangle up enough materials to craft a servant coffin, you'll get the Dominate Human ability—access this by pressing CTRL and selecting it in the radial wheel. Though it disables your spells, this state gives you access to Subdue Human, which you can use on weakened human enemies to lure them back to your castle. Different enemies have different abilities, but generally, higher blood percentages make for better thralls.
Once there, activate the servant coffin to inter the enemy and wait until they're finished cooking. You can't do all that much with your vampiric thrall initially—they'll just hang out and guard the castle, though they will potentially die if there are dangerous enemies lurking. Don't worry too much, though; you can always revive them via their servant coffin.
As you continue the tutorial quest, you'll eventually get the castle throne, and this is where you can start sending your servants out to hunt enemies and pilfer resources. Before you do, make sure to equip your thrall with some armour and a weapon, since this will help them tackle tougher enemies and make it back alive with your precious plunder.
