This is my favorite Basic Weakness, and I'm writing this review in the hopes that future game designers can take a hint on how to do mechanics like this well.
First of all, while by far my favorite, it is not the card I would chose to put in a deck (not that any of us would pick and choose with a random card selection, right? Riiiiiight?). But when I draw any other random weakness, my thoughts tend to range from "okay, I can deal with this," to "aw, crap. This is gonna be a pain to deal with." The Thing That Follows is the only Basic Weakness that instills an actual emotion in me- a sense of giddy dread.
This card is like a well paced horror movie. It makes every draw an anxious roll of the dice, wondering if this time the unseen Thing is going to crawl out and mess up your day. And while that can be said of pretty much any weakness card, the trick of The Thing That Follows is how it repeats itself. Once you draw the card, the cycle of tension repeats as it moves closer and closer to you across the map. Even if you manage to beat it into submission (not all that unlikely with its stats, but hard enough to mess up some endgame plans), it just returns to your deck, only this time with significantly fewer cards on hand to lower the chances of picking it up again.
It is a masterpiece of the tension/release cycle that is crucial to all forms of horror. Long buildups of dread as you feel it coming, punchy moments of action as it resolves, and repeat. Not scary because it ruins your day, but because no mater how many ways you find to deal with it, it always Follows.
Helping matters is that it's one of the most narratively cohesive Basic Weaknesses out right now. (What, exactly, does Paranoia have to do with resources?) But with the Thing, everything from the name to the art to the quote to the mechanics all serve to instill that key emotion. Not fright, but dread. Consuming, unavoidable dread.
Bravo, Fantasy Flight. You've made a business out of turning Cosmic Horror into game mechanics, and with this one you knocked it out of the park.