The only real use for this card is as an Oath of Druids enabler, but Oath is banned in Legacy and if youre playing Vintage but you cant afford a set of Forbidden Orchards, youve got bigger issues
They come with great abilities on the attack, are hard to block or even better come with evasion
Perhaps you make copies of massive threats like Ancient Copper Dragon and Bloodthirster, or you triple up on powerful enters abilities from Solitude and Seasoned Dungeoneer
With more Magic-y flavour, you could imagine this card appearing in the dice-rolling set of Adventures in the Forgotten Realms
Tracking info hits your email so you can watch it move toward your door
If you have a lot of relevant permanents such that their Detention Spheres always have targets but yours might rarely have non Detention Sphere targets, you might need Banishing Light so that you can remove their Detention Spheres with a card that would otherwise be dead, having no other target than Detention Sphere