- This is the level of light as outside on a sunny day, or inside a fully stocked and attended Dwarf feasting hall, etc. Anything brighter then this is clearly supernatural, from another dimension, and so on. No penalties for actions; creatures of darkness like orcs or cavern beasts will instead get a penalty of -2 on their rolls instead from the intense, blinding light.
Torchlight- The level of light produced by a torch, huge jar filled with fireflies, a magic Light spell, cavern filled with luminous mushrooms, and so on. No penalties for actions.
Candlelight- The level of light produced by a single candle. As should be mentioned here; light levels are not cumulative. Two candles still counts as the candlelight, but additional sources of light will help prevent your lights from being snuffed out. As in no amount of candles equals a torch, unless you've literally covered an entire room with them or some other ridiculous situation. Creatures who rely on light to see get -2 to all attacks and saving throws.
Matchlight- The level of light created by sparse, inconsistent, or otherwise very poor light. Also called "Dim" levels of light. Might be created by a few scattered, loose torchbugs in a room, a single glowing mushroom, or striking several firestarters and going by the sparks and flashes. Character who rely on this light get disadvantage OR -4 to all attacks and saving throws.
Total Darkness- No light at all. In this scenario, characters cannot fight at all. Only using some kind of supernatural blindfighting, or in a lucky 1 in 20 chance can you actually hit an opponent with an attack. You also cannot cast spells, as you cannot see or visualize your target, depending on the spell being cast. Total Darkness may also nullify your saving throws against monster abilities; you cannot dodge the sucking, swallowing mouth of a giant monster unless you can see it coming, as such total darkness is the absolute most dangerous situation and should be avoided at all costs.