Lore of Life Question

Ok this may sound dumb but the language seems odd or I can just be over analyzing this. Throne of Vines says "...spell cast upon the Wizard." Does that mean only the wizard who knows the spell can cast it on himself or can that wizard cast that spell on another friendly wizard? I know sounds wordy. But I appreciate it.

The target can only be the wizard casting the spell in this case. So no casting Throne of Vines on a Lore of Shadow/Death mage to help prevent their inevitable miscasts.

Pointless in my Forest Spirit army since Branchwraiths are only L1 Casters

Ya, Branchwraiths are mainly there to give 5+ regen.