Bigger enemy, more clues. Simple, effective. If a little specific.
This is not a Bread & butter upgrade, it is'nt nearly catch-all enough. But it's a brilliant way to spend 2 XP in order to keep your deck synergy functional, I.E, rather than upgrading from Evidence! into something completely different, you get this small boost that keeps the card revelant in the long run.
This ought the be among the last 30-something XP you spend in a deck.