FFXIV released their newest job, the Blue Mage, last week. The Blue Mage is a "limited job". It currently has a level cap of 50, and is not allowed in normal random-matchmaker group content. You can do dungeons and trials with a Blue Mage, but you have to be in a pre-made group.
The central mechanic of Blue Mage is that you don't learn abilities from levelling up, like all the other classes. Instead you learn abilities from monsters. You have to attack a monster, see it use the ability, and then defeat it. You then have a chance of learning the ability. There are currently 50 abilities to learn, of which you can equip 25 at a time.
The big problem, as I see it, is that the game doesn't give you very much information on what abilities you can learn. The spell book starts blank, with 50 slots. The only information given is the zone in which a monster with the ability can be found. It doesn't even tell you the name of the spell!
Now, obviously, all the information was data-mined and there are guides already up on the internet which will direct you to all the monsters you need.
But if you want to try and do it organically, you basically wander around attacking every monster in the zone. And since learning an ability is not guaranteed, you have to kill several of that type to be confident that you can't learn anything.
The saving grace of the system is that most abilities can be learned from several different monsters, not just the ones from the zones noted in the book.
What I'm currently doing is just finishing FATEs to level my Blue Mage, and incidentally learning abilities along the way. I can't target specific abilities, but the spell book doesn't tell me what abilities I can learn in any case. So far it is working pretty decently. I'm level 12 and I've learned 5 abilities or so. Among them an AoE bomb spell from goblins, a cone stun from Quirin, a "Sticky Tongue" pull from giant toads, and a self-destruct spell from bombards. Not really sure what use the last is, since it does kill you, but maybe it will combo with something.
I rather imagine I'll end up at 50 and then look up an online guide to get the abilities that I'm missing.
I do think it would have been better for the spell book to give the names of the abilities, but not the locations. That encourages the player to remember what monsters use the abilities. As well, if you're fighting a new monster, you know if you can't learn the ability, rather than wondering if you are just unlucky. Another option might be some sort of Lore spell which tells you if the monster has a learnable ability.
Still, FFXIV's Blue Mage is an interesting experiment. It's more of side-content, rather than a straightforward combat job, but it is enjoyable so far. It's a bit of a shame that the internet has already obsoleted the exploratory aspect.