Spoiler for those that struggle with the spiders in the well:

There is also a cantrip that lets you cast light on an object. It's great if you're a human cleric/wizard . I just cast it on my human/cleric and it was so good .

I also noticed "Dancing Lights" versus the "Light" spell, both as wizard cantrips, on character creation. Frankly, didn't see a huge difference. (Here's how long it's been since I played D&D table top) Last time I saw Dancing Lights, it was a level one illusion that had a chance to hypnotize. Did see that in the description here, and since I didn't notice a difference, I chose Light instead. I use it the same way as FatePeddler: cast it on myself, and I'm a walking beacon. Doesn't help while trying to be sneaky, but I'm not split class Wizard/Thief...although split class in D&D 5e is kinda useless now, the way I read rules.

There have been a few posts about struggling with darkness. I guess that's another problem with coming to game without knowing the background rules. In PnP D&D, a Light spell was often the 'go-to' option for illumination, including loosing Light arrows into dark corners, dropping Light pebbles down wells, Light on the front of shields and so on. The old Continual Light was even more popular, and few wizards went anywhere without a Continual Light on the end of their staff (with leather cover for being circumspect).

Yes, this game actually makes light spells important. And fortunately you can get an item that gives you the dancing lights cantrip if you didn't know to take a light cantrip.

I use that item a lot on my Human Warlock, but it is behind a DC 18 or DC 20 check. Ranged Characters can be helped by using the Light Cantrip onto a throwable object like a skull and tossing it to the destination.

You don't need the DC check in dark areas, you just put it next to any enemy that has concealment from darkness, and the concealment goes away.

There is actually a major difference in terms of tactics and how you use the spells. Light has a 1.5 m range but can be used on objects that you can throw/ people who can move around (the latter is a bad idea if you're trying to sneak). Dancing Lights have an 18 m range but stay in place once cast; this is nice to illuminate enemies concealed in the shadows, and so on, but beware casting this at your own location and messing up your own concealment.

The Dancing Lights necklace you are referring to requires you to pass a DC 18/20 check to receive it as a reward.

Oh yes that.

Save scum.