Vortex

What is the Dimensional Vortex?
Also simply called the Vortex, this is the place where all non-World Map missions are stored.

(Note that the Arena and Colosseum are separate from both the Vortex and the World Map, but the fights you can have in these areas of the game are not considered missions, as they give no experience or gil.)

How do I reach the Vortex?
There are actually a few ways to get to the Vortex, but they all go to the same place, so for the most part, you'll reach it simply by tapping the large, swirling button marked "Vortex" on the Home screen. There is also a smaller version of this button at the top of the World Map overview, if you find that you'd like to jump directly from the map to the Vortex without returning to the Home screen.

Less important: The other way to reach the Vortex is to explore the Farplane, a magical realm populated with moogles. However, for the most part, the Farplane is just a pretty graphical shell that houses the Vortex and a couple of other minor things, so there's generally no need to visit the Farplane just to access the Vortex. If you'd like to see it anyway, just to explore, you can find the Farplane Monument (floating rock shard) in any town on the World Map, and touch it to be transported there. You can also access the Farplane by tapping the Exchange button at the top of the Vortex menu, but we'll get to that later.

Navigating the Vortex
Navigating the Dimensional Vortex couldn't be easier. When you go there, you'll be presented with a list of buttons, each containing various different missions: These missions are laid out in a regular way, so as time passes you'll get used to it. For now, use this quick guide:
 * You can scroll up and down through the different missions by dragging with your finger. There are usually more than will fit on one screen.
 * Tap on a mission banner to see what level(s) is/are available, and what their NRG costs are. There are many different kinds of missions in the Vortex, and some cost more NRG than others.
 * When you defeat one difficulty level of a mission, the next-highest difficulty level will unlock.
 * Tap the level of the mission you want to play to enter team setup and prepare for your fight(s). You can still back out any time before tapping the "Depart" button.

Time Limits in the Vortex
Not every quest in the Vortex will always be available. The more permanent/recurring a Vortex mission is, the farther down the list it is placed in the Vortex, and vice-versa. At the very bottom, there are 3 missions that are permanent: These missions are always available to you. There is no need to rush to finish or experience them.
 * Vortex of Desires
 * Chamber of the Fallen
 * Training the Soul

Permanent Vortex Missions

 * 1) The Vortex of Desires is a place to grind for various things, including experience, gil, materials, and more. You can unlock one themed chamber per day for free; after the first, unlocking more chambers costs 100 Lapis per chamber. Do not waste your Lapis on this; nothing in any of the chambers is worth spending 100 Lapis to get it now instead of tomorrow. That said, the Vortex of Desires can prove very useful for newer and moderately-experienced players. Look at the Chamber of Experience and the Chamber of Awakening in particular, to help you maximize your characters' power.
 * 2) The Chamber of the Fallen might be considered the "end-game progression" area of Exvius. It is full of optional bosses who drop powerful rewards. The weakest bosses (which are still plenty tough) are at the bottom, while the newest and strongest are at the top. Newer bosses also have weaker forms you can fight for practice (look for a varying NRG cost on the button), but they're still challenging. Even I am only about halfway through this list.
 * 3) Training the Soul is a series of moderately difficult quests that will grant powerful gear to your main characters, Rain, Lasswell, and a third companion you may not have met yet. It is intended for experienced, max-level parties, so you don't have to worry about it for a while yet.

Above these three missions in the Vortex will be recurring missions, if any are active. These missions are not always available, but will occasionally reappear, usually on or around the weekend, and offer different and/or better rewards than the Vortex of Desires.

Recurring Vortex Missions

 * 1) Cactuar Dunes: Fight your way through a few absurdly-easy metal cactuar enemies. When you kill a metal cactuar, it will turn into a unit on your character roster. You can fuse cactuars to your regular units to give the regular units a massive experience boost. This is a great way to get a new character leveled up fast, but because it's so quick and easy to repeat, it will feel like it drains your NRG in the blink of an eye. Nevertheless, highly recommended, especially for newer players.
 * 2) Chamber of Crystals: Fight a few waves of enemies who will drop some Magicite for you to feed to your Espers. Once you have reached and cleared the Phantom Forest area on the World Map, you'll get better Magicite returns on your NRG from the Phantom Forest Exploration quest, so I recommend trying it out once (for the extra Lapis you can get from completing the optional goals), then skipping this one for the most part.
 * 3) The Enchanted Maze: Enter a short exploration map and choose one of three doors in each room. Guess right, and you go to the next room; guess wrong, and your trip will be cut short. In each room, you'll fight one or more enemies that convert into useful units (for sale or fusion with your regular units), and be granted one resource point with rare items in it. Even though the layout is totally random on each visit, the Enchanted Maze offers a great average return on all sorts of useful items for new to moderately advanced players. I highly recommend visiting it whenever it opens up.
 * 4) Gil Snapper's Cave: Fight and capture Gil Snappers, turtle-like bonus units that can be sold for massive amounts of gil. Gil is easy enough to come by in the rest of the game that it's hard to recommend this one, but I guess if you were really desperate for character awakening money, and it was sitting right there in the Vortex, you could consider it. In most cases, though, exploration missions will be a better use of your NRG (and the Enchanted Maze, which contains Gil Snappers and other useful units, is also a superior choice).

Reappeared Missions
Every now and then, above the weekend and permanent missions, you might see a unique-looking banner with the word "Reappeared!" written on it. These are previous limited-time Vortex missions that have unique rewards, but which are being reopened to help newer players to be able to go back and get rare or useful equipment. These are often a little easier than the current limited-time missions, especially at lower difficulty levels, so feel free to take them on as far as your team will carry you whenever you see them. Reappeared missions are not very common.

Limited-Time Missions
These are the missions announced on your bulletin board every week on Tuesday, and opened every Friday. Each one will be around for 2 weeks from its first appearance. These missions typically come with princely rewards for participation, even at lower levels, so play them as much as you can, if possible, until you've cleared all difficulty levels or gotten to a sticking point. The unique gear and abilities you can earn from these missions will not typically be attainable again after the event period ends. There are many different formats that limited-time missions can take:
 * 1) Exploration missions: You can tell these apart from regular combat missions because the buttons for the levels are green instead of red. Each level will feature treasure, random enemy encounters, and a boss at the end. Beating one difficulty level will typically allow Rain and company to explore farther on the next map, and so on. Randomly encountered enemies also get tougher at each level - not just the bosses. These missions tend to offer good equipment rewards, but they get significantly tougher with each new unlocked level of difficulty, making them potentially frustrating for less-experienced players. There is also not much of a point to replaying these missions once you've cleared them, making them one of the lesser time and NRG investments available from a limited-time quest. (Depending on your point of view, this can be a good or a bad thing.)
 * 2) "Currency" missions: A series of regular combat missions that grant some kind of special currency. Typically, you  can also bring characters along in your party that are related to the theme of the event (the bulletin board can tell you which ones), and if you do, you will get even more bonus currency. The currency can be traded to King Mog in the Farplane for all kinds of stuff. King Mog is pretty generous, and he offers a wide range of useful items it's hard to find elsewhere, plus some unique equipment and/or abilities each time as well. These missions are often quite useful for players at all levels, because you can trade your currency for whatever rare or costly items you need at the moment.
 * 3) "Story Event" or filler missions: These consist of a series of map locations on a custom map. Each location has several series of fights laid out on yet another map, bookended with story cutscenes that fill in some side story details on one or more of the main characters. (It's easier to understand when you see it.) You have to complete every fight in the map location (which costs a big chunk of NRG) or you don't get any reward from that location. These missions are decent for gaining EXP, but their main purpose is to gather Crysts, special items for ability enhancement. There are also useful awakening items, limited equipment, and other prizes available, so don't pass Story Event missions by without looking, but since ability modification is a late-game-only concern, these missions are a somewhat lower priority for newer players.
 * 4) Raid missions: Instead of spending NRG on these missions, you will be given 5 Orbs that replenish at a rate of one per hour, similar to the Arena and Colosseum. You will fight a single, powerful boss each time you undertake the mission - no underlings or warm-up fights here - and the boss will gradually "level up" as players continue to damage it. At the end of each fight, you get a special currency (Raid Coins) proportional to the damage you dealt and the boss' current "level." Raid Coins can be spent (100 at a time) in the Summons screen to perform "Raid Summons" for special crafting materials, money and EXP-augmenting units, Magicite, rare combat characters, and more. You should always do Raids when you can, because they grant EXP despite costing no NRG, which is extremely rare anywhere else in the game. In addition, the rewards you can get from spending raid coins are often pretty decent, especially in terms of free Magicite and Cactuars/Gil Snappers. A few more notes about raids:
 * 5) The boss' "level" is actually not related to its combat ability. A raid boss doesn't get tougher when its level is higher, but it does grant a better Raid Coin bonus upon defeat. Therefore, you want the boss' level to be as high as possible, so you can get as many coins for each victory as possible. This is accomplished by dealing as much damage to it as possible. Don't hold back!
 * 6) The boss's "Level" meter (on the mission select screen, not in battle) is shared by all users, and it's all of you dealing damage to it together that drives the meter down and forces the boss to level up.
 * 7) Even if a raid boss wipes out your party, you will still get raid coins proportional to the damage you dealt. Therefore, it's advisable to throw everything you've got at the enemy if it seems like you're about to lose. There's no penalty for dying, except that you don't get as many raid coins as you would otherwise have been able to, so if all else is lost, hammer it with your strongest attacks!
 * 8) As with almost all Vortex missions, defeating a raid boss at one level of difficulty will unlock the next level, and so on. The boss gets tougher with each new level, but the bonus multiplier you get for dealing damage to it also goes up drastically, so as weird as it sounds, it's sometimes better to attack a raid boss at a level where you know you can't win, but where even your partial damage to it will actually multiply into more raid coins than a complete victory at a lower level. Feel free to experiment.
 * 9) Raid coin bonuses that depend on the damage you deal to the boss don't consider any damage beyond an amount equal to the boss' maximum HP. This is to prevent powerful players like me from abusing the system by hammering weaker versions of the boss (with lower defenses) and getting huge overkill bonuses.