So when you're level 1 your first Hornet shows up as equal (well that's to be expected because no mob can be lower level than 1) yet it's incredibly easy to defeat. Probably you have to do something really stupid to die before reaching level 2.
Now roll some weeks forward and I'm level 18, returning to Bastok after partying at the dunes so I can start my subjob. While traveling through the highlands I thought that I'd just solo everything that checks as easy prey for a few extra exp - and almost got killed by a mad sheep (only survived thanks to a Cure II at the last second).
So the big question is - How do you actually tell whether you're good enough to solo a specific mob?

Generally speaking, the higher level you get, the more effort/preparation you have to put in to fights.
Think of it like /check takes in to account your full arsenal, if you'd like.
At level 1 you can really only cast Dia and auto-attack. By level 18 you have debuffs and cures. Expect to have to use these.


Edit, OT: You should be safe to take on Easy Prey mobs most of the time.

I did eventually defeat them all but I had to keep debuffing them and healing myself repeatedly and still ended up with 30% HP and virtually no MP. I'd like to know whether it actually gets even more difficult, e.g. if you're level 50, can you solo all mobs in the dunes?

So, the /check text describes what level the mob is, which is obvious.

Assuming the mob is a Mad Sheep (lets say it's level 14), and you're lv18 and it checks as Easy Prey; you should easily be able to defeat it with the amount of skill your character can gain at that level, through capping your combat skills (Evasion, Parry, Guard, Sword, Elemental Magic, whatever it is your character is using).

Capping evasion helps a lot at lower levels and so does capping your combat skills like your melee skill or magic skill. These improve your accuracy and attack (melee combat skills) and accuracy (magic combat skills). This allows you to hit the mob more often, evade/block/parry more attacks and land unresisted magic that will deal more damage or land debuffs that will stick more easily.

You don't need the best gear at these levels but this helps a lot with the combat in FFXI. You should be able to kill up to Even Match or even Tough depending on your job, whether your skills are capped, whether you have all the magic you need and have decent enough gear. Getting a subjob helps a lot as it boosts your stats straight up from the other job, so getting that is a good step to becoming more powerful.

Later on, it becomes more difficult to solo higher level mobs, but it works out the same as what other people have put in this thread, you will probably have to use all of your abilities/spells per fight unless you find a particularly exploitable mob type; lets say skeletons and you bop them with your MNK super easily, or maybe a mob family that dies super quickly to your magic because of its lack of HP. Generally solo you want to kill Tough and maybe Very Tough mobs if you can chain them easily with minimal downtime, otherwise breezing through easy prey with capped skills is doable at any level. I'd say it gets easier to kill Tough, Very Tough or Incredibly Tough mobs solo at 75 depending on what job you are using.

This was unnecessarily long but you get the point; what job/race combination were you playing as to nearly die?

it will be harder if it’s your first job with no sub job because you’re missing some of your stats. Also your combat skills are not capped

Also some jobs are better at soloing than others and some enemies are harder to Solo than others. You just have to pick the stuff up with experience.

RDM is known for being pretty good at soloing, but at your stage you’re missing some key pieces that help a lot like refresh convert stone skin and haste

I was RDM/hume. I think only evasion was capped, probably because mages don't get to melee a lot when partying. I was equipped with Scale Mail and Spatha. Had Cure II, which turned out to be the difference between victory and defeat and always used Dia & Blind, sometimes also Paralyze, Poison.
Maybe I was just not being careful - I took on some other mobs as well and they were much easier, though I had to use Cure at least once in every fight.

Slow will help a lot

Ah yeah, that would explain it if you invest into a fire/flame sword, those are pretty awesome at the level you get them; yeah healing and buffing your character becomes quite important later on.

I'd say RDM is one of the jobs that becomes a little harder if you're not skilled at using all their spells but if you cap everything and face off against Tough, VT or IT you can win most fights with debuffs and buffs on yourself, and it is very fun as well! Soloing the RDM testimony from mobs and beating Maat are interesting with RDM since there are many ways to do it.

I'm presuming you're new, and as such I wouldn't worry about soloing too much as it requires a bit of knowledge.

As mentioned be sure to use the /check command to see how difficult a mob is, for the most part you don't want to fight anything above "Decent Challenge" as an "Even Match" or "Tough" can easily destroy you unless you know what you're doing (Don't even think about Very Tough/Incredibly Tough). These are very loose rules as there is a wide variety of monsters which are easier/harder to fight by theirvery nature regardless of their /check difficulty or level.

For example;
- Saplings are very simple to fight as they do light damage and can sleep you, but nothing too serious
- Crabs are fairly straight forward and harmless, although fights will probably last a bit longer since they are defensive
- Lizards can be incredibly dangerous as not only can they Petrify and Silence you, they have an extremely damaging and lasting Poison attack which you die from out of battle regardless how easy it was to defeat

Job choice changes everything; when you check a mob, its reading will vary depending on the level difference.
High evasion means it has higher evasion than your accuracy stat, high defense means its defense stat is higher than your attack stat.
Because nasomi doesnt have ilvl (meaning your gear/stats are unaccounted for, besides what can be seen from /checkparam <me>)
What you can and cant kill will vary.