It is very unclear how to tame it. From what I can tell.

1. Blood stalker can be tamed on the floor.

2. There is a bug where they throw u away while dragging you in.

The way to tame:

The blood stalker starts with 50% taking efficiency. Breed some relatively small animals (I bred parasaur, but moschop are also great)

(I am not sure, but have the bloodstalker grab you at the start. So that it’s in the taming list and you can see the taming efficiency)

Throw the animals into the bloodstalker’s range and have them kill it (just killing. Doesn’t require grab)

Throw your tames until 100% efficiency.

Have the bloodstalker grab (they need to grab you, hitting you doesn’t count) you. And just wait until it eats your blood pack and get tamed.

I would recommend grabbing them with wyvern, throw them in a rather flat safe area. And do whats mentioned above.

If you have trouble making it grab you. Just go on a rock they can’t reach like how you tame other animals, lol.