I had a lot of ideas in my head but I decided to choose one that will be most acceptable:
My suggestion to improve Blood Caller is adding him ability Anchored.
And now, a short explanation of why I decided that is the best solution:
I just asked myself what worst that could happen after playing this card?
Sure you will think that killing it. The answer is rather different.
Returned to the hand or take control of this card is the worst thing that could happen to this card.
By returning Blood Caller to hand opponent is doing life business because playing a card with a cost of 3 gets rid of three of our cards.
Additionally, after being returned to hand that card becomes useless because it will be very hard for the 2nd time to play.
When it comes to take control of this card opponent will be able to laugh out loud in your face.
Finally, a few words to people who will mark "NO":
If you want to do this then you have obligation to give an argument for your choice in this topic.
Otherwise, it will confirm that someone has not grown up yet to play this game (and this game has a low minimum age).