You don't get it, the stupid mechanic is that they have to be standing on it, the stupid part about it, is that its a Lantern it should give you surrounding vision, not just if you stand on it. Gragas barrel gives surrounding vision and its a barrel, an inanimate object with absolutely no light source, is granting surrounding vision. And also I said nope to surrounding vision lol. Basically if you took 2 unwarded bushes, side by side, and threw a barrel in one, the whole bush would light up and some of the ground in the area near it. If you threw a Thresh lantern into the other one, you would notice that every part of the bush is unseen along with the ground near the bush, the enemy HAS to step on the Lantern in order for you to see them. At least when I played Thresh I couldn't see them until they stepped on it.