This is probably the strongest triple-class booster card of them all, maybe with some competition from Crafty. The combination of Fortune, Spell, and Spirit covers a pretty impressive array of cards. While this includes some Spell assets, most of the power here comes from events - so it's particularly good with event-based investigators like Patrice or Parallel Agnes. But I think it's a real workhorse for any Survivor that might splash into the Guardian or Mystic side of of the trifecta (or maybe vice versa).
Some of the best survivor cards like True Survivor, Will to Survive are ordinarily held back by their cost, but receive a strong discount through Prophetic. There are less dramatic staples that no survivor would mind discounting: nobody will say no to a free Eucatastrophe, "Look what I found!", or Lucky!. If you're running a bless build and draw into Keep Faith, you can just throw it out as soon as you want without caring. It plays nicely with Dark Horse since it's a pool of replenishing credits outside of your own bank.
Honestly, it's so good with Survivor toys I'm not sure I'll ever run On Your Own over it again. OYO has consistency, resource cost, and deck space considerations going for it ... but Prophetic is so strong and flexible I'm fully willing to draw & pay for it if it means I can play with allies too.