I assume that you still remember when you were here for the first time. You will have to click on a small opening to go back to the crypt, because the main entrance has been sealed off. Enter the tomb and reach the area with the rope (screen). Use the rope to get to an upper level. Go up and turn left at the junction. Click on the door which protects you from entering the main area of the tomb.
Thankfully, it's going to be extremely easy to solve this riddle, because you know possess all the necessary items. All you have to do is to place them correctly:
disk - central area of the door (screen)
mirror - western branch
garlic - eastern branch
sphere - northern branch
holy water - southern branch
You'll find yourself standing inside a very interesting room with a large object that looks like a portal to an alternate dimension. I would recommend that you follow my instructions and perform all actions carefully. Your first task will be to obtain a weapon. As you probably remember from the first verse of the riddle, you will have to find god Seker. Click on a fallen statue (screen) and when you're unsuccessful, use an axe on it. Pick up a Silver spear tip.
The second verse of the riddle tells about a bloody altar. You can find this object to the left of the portal (screen). Click on it and wait for Van Helsing to get there. There are some hieroglyphs on the altar and you will have to compare them with those from the black sphinx.
This is going to be a very simple challenge. All you have to do is to compare symbols from your diary with those on the screen. Start by clicking on 1 (screen) and finish the puzzle by clicking on 6. Wait for the altar to turn around, allowing you to collect a sample of the blood. You will have to use Receptacle here.