Every adventurer lurking through dungeons risks getting caught in one of the darkness spells, such as Darkness or Deeper Darkness. Not being able to see anything because of such spells is a sure way to a Total Party Kill. How can one deal with those spells at lower levels (8th or lower)?
Dispelling with light spells
Because light spells have a range of “touch”, dispelling can get tricky and dangerous. You'll need to find the object on which a darkness spell was cast and touch it. If darkness comes from an at-will spell-like ability, you are screwed if you try to compete with it using limited resources such as spell slots.
Requires you to ready an appropriate action and is generally considered an inferior strategy: instead of readying an action to counterspell, it’s usually better to ready a damaging spell or to disable the enemy. Also, if darkness comes from a spell-like ability, it can’t be counterspelled.
Dispelling with Dispel Magic
Dispel Magic has a Medium range, allowing you to dispel from a distance. However, it requires a caster level check and line of effect.
If something grants you Darkvision, for example, your race or this spell, you can see in normal darkness. However, not in supernatural darkness caused by the Deeper Darkness spell, and nor can your allies see in darkness unless they also possess Darkvision.
Get a light spell of higher level
Hire an NPC to cast a Continual Flame that was Heightened to level 4 on your Dull Gray Ioun Stone. This will shine through all the darkness spells of levels lower than 4 (namely 0, 1, 2 and 3) or spell-like abilities functioning like them. This will cost you 25+7*4*10=265 gp. Ask your GM if they allow buying metamagic’ed spellcasting services. Once you get your own level 4 spell slots, you can perform this procedure yourself.
A simple Ioun Torch wouldn’t help, as, per the “Illuminating Darkness” blog post, it won’t be able to penetrate even a simple level 2 Darkness spell. Even if you persuade your GM that the spell cast upon it comes from a Cleric, not a Wizard, Deeper Darkness will still mean getting screwed.
Buy a scroll of Daylight and a few mundane torches
The aforementioned blog post says that even if Daylight cannot suppress all the darkness spells by outlevelling them, lighting simply defaults to “ambient” and you can use non-magical sources such as torches to light your way.
For just 5 gp, you can buy a spring-loaded Wrist Sheath and draw a scroll as a swift action. Ask your GM if they provoke attacks of opportunity and if scrolls count as “one forearm-length items”: your mileage may vary.
Scrolls of Daylight can be of limited use, though, because the darkness you're trying to overcome can prevent you from reading the scroll if you are already inside it. The potion version, Oil of Daylight, is often what you want. Even though it costs more, it's worth it because it's an emergency item.
Use Unwelcome Halo instead of Daylight
As clarified by Mark Seifter, a member of the Pathfinder design team, because Unwelcome Halo uses the same wording as Daylight, it should be able to penetrate any darkness spell of any level, at the cost of just a level 1 spell slot.
So, instead of scrolls of Daylight, you might buy scrolls of Unwelcome Halo, costing 25 gp each. Do you expect to fight darkness spells? Prepare Unwelcome Halo or two, it shouldn’t hurt much. Do you fight creatures with darkness spell-like abilities on a regular basis? Buy a wand of Unwelcome Halo!
As of August 2019, this solution is fully PFS-legal, but your GM might or might not consider applying physical violence if you solve entire darkness-based encounters so cheaply.
Note, though, that Unwelcome Halo’s radius is 3 times less, making the illuminated square 9 times less. At some point, Daylight will also become affordable and can hence be preferred.
Oil of Unwelcome Halo could be more useful than a scroll for the same reason as Oil of Daylight.
Be a level 8+ Cleric of the Sun domain
While level 8 can hardly be considered a “lower” level, someone who attains it and has a Sun domain can use Nimbus of Light, the level 8 domain power.
See in Darkness ability
This ability allows you to see even through supernatural darkness. There are some spells that grant it, there are Tieflings who can take the Fiendish SIght feat twice, Rogues with Darkvision can take this Rogue talent, and some very expensive items that are probably too expensive for parties of levels mentioned in the OP can grant See in Darkness.
- Scrolls of Unwelcome Halo (25 gp each) and scrolls of Daylight (375 gp) return the light level to ambient (default) no matter the level of the darkness spell in question. Torches (1 sp each) and similar non-magical means can be used then. - If your GM allows, load your scrolls into spring-loaded wrist sheaths.
- Heightened Continual Flame of level 4 can overcome most applications of darkness spells. Even if it doesn’t, it’s not lost, but rather merely suppressed for a time.
- If you happen to be a Cleric of the Sun domain and got to level 8, you are lucky, as you got a special power to fight magical darkness.
- If you have Darkvision or can easily obtain it, non-supernaturally dark rooms are visible to you.
- In some cases, it’s possible to get the See in Darkness ability and ignore any darkness altogether.