Change player selected target

Good night, I’m trying to fix some spells, and I’m stuck in a part of Prismatic Crystal mage spell, the problem is when the crystal is just summoned, the player selected target must change to the crystal, I’ve been trying the SetTarget() and SetSelection() functions with crystal summoned GUID but either does not work, the selected target not change. I’ve been researching and I read that there is not SMSG opcode to change target but only to clear target which is SMSG_CLEAR_TARGET, and any opcode in server side to change the current selected target, as it does in retail, could you help me giving me some orientation about how to make player target the crystal when the spell is casted?

Video to see how it works:

Thanks for you time.

@timh52280 Try asking in Custom Codes. This is more specific Help getting the server running, not custom codes.