After showing Dracula's Heart to the Ferryman, he takes you to the entrance of Brahm's Mansion.
Find the Gypsy
Go to the right and jump over the spikes. Go up the stairs, kill the Knight, then go to the right and go up the next set of stairs. Kill the Skeleton there, then go up the stairs there.
Go to the left, killing a Knight and a Slime. You will find more stairs, so go up, killing the Skeleton there, then go up the second flight of stairs. Go to the right and kill the Skeleton, then go up the stairs and kill two more Skeletons. Go up the stairs after that, and kill the Gargoyle. From there, go to the right, killing a Knight along the way. Keep going to the right, then when you can jump down, do so, using your weapons to deal with the Gargoyles down below. Go to the right and go down the stairs, killing the Knight at the bottom, then go left to the next screen.
Go to the left, killing the Knight down below. Jump onto the platform where the Knight was, then if you need an Oak Stake, jump up to the left to where the Gypsy is, and buy an Oak Stake.
Go to the Boss
Make your way down the platforms, killing Knights as you go, until you are at the top of some stairs. Go down those stairs, then kill the Skeleton and go to the right, where there are more stairs. Go down those, then go to the right. You will be in a chamber with some Bats on the ceiling. Go to the right to reach another room.
Go to the right side of the Reaper and throw the Sacred Flame at it. While the Reaper is stunned, attack with the whip. Repeat this process until the Grim Reaper dies and drops the Golden Dagger. This weapon costs 2 hearts per use. When you throw it, it doesn't stop until it hits an enemy, at which point it bursts into flame, and the flame will damage any enemy that touches it.
Get the Piece of Dracula
Go to the right from the Grim Reaper's room. Go up to the platform with the glowing orb, then throw the Oak Stake at it. Jump onto the bag to get Dracula's Eyeball. If you equip it, you will be able to see the invisible clue books that are hidden around the land.
Leave the Mansion
Go to the left (ignoring the Grim Reaper) until you find stairs. Go up the stairs, then go to the left and go up the stairs there. Kill the Skeleton and go to the left, going up the stairs there. Kill the knight, then go to the right and jump onto the platform, then jump up onto the next platform. Kill the Knight and make your way up the platforms. You can buy another Oak Stake from the Gypsy to make things easier for yourself in the next mansion. Then go to the right until you find some stairs. Don't go up those stairs, but instead go to the right to reach the next screen.
Go up the stairs here, then go to the left and hop up the platforms, then go to the left to the next area. Go all the way left until you fall down the ledge. The wall to the right is fake, so go through it and fall down below. Go to the left and go down the stairs, walk to the left to fall off the ledge. Go to the right and go down the three flights of stairs, then go to the left and jump over the spikes, then go left to leave the mansion.