devtrackers.gg
Thats honestly how I initially thought they would work. But after testing them for a while (aka blowing upwards of 700k favor on them) aswell as talking to other people, it seems they are hardcoded for 1LP which is, as you said, a total waste of favor.
This is not correct. It sets a minimum of 1LP, so if the item would have dropped with 0LP, it drops with 1 instead. It can still drop with 2 or more, but the chance of that is the same as normal.