The FFBE wiki will provide you with already a lot of answers, please check it out.

The daily help megathread are here for a reason, please, use them. To view stickied threads, sort by hot.

If you need friend, use the megathread or the LFG thread (if one is needed for the current event.).

Beginner guide by /u/3DJutsu

Basic acronyms survival by /u/DraK4y

Stat Pots Calculator by /u/chippou

Facebook account suspended? There's a way to get it back!

You can find the ongoing event Megathread if you filter by top as they are stickied.

Event currency will most likely NEVER come back. You can always sell them after the events ended.

End of the Story

Forgotten Wall

Guides/Website you should bookmark.

Esper/Unit Calculator by /u/dbarchitect

Stat Pots Calculator by /u/Chippou

Equipments Database by /u/CloudToucher6

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Art of Chaining by /u/lekkin007

Esper and you by /u/realised

Quest, Vault Keys and Exploration Spreadsheet by /u/maplethesyrupcat

Equipments/Abilities:

• Doublehand increase the potency of ATK GEAR by 50%, so that mean Hyper Wrist(s) will give 15 ATK, Tiger Mask will give 21 ATK etc.
  
• On GL you can't stack abilities if they all come from ability slot(s), if you want to stack them, they have to come from different mechanism, so esper, equipment, innate on that unit or from Materia slot(s). The abilities affected by that restriction are: Doublehand, Killer Passive and Weapon Mastery. Abilities that increase stat like 10% ATK can be stacked from Materia/Gear with a limit of 300% to that stat.

Units/Awakening:

• There is 4 units that have no other utility then to be fused/sell:
  -Metal Minituar/Metal Cactua/Metal Gigantuar, their only use is to give unit exp (5k/10k/30k);
  -Mini Gil Snapper/Gil Snapper/King Gil Snapper, their only use is to be sell for gil (1k/2.5k/5k);
  -ATK/DEF/SPR/MAG/HP/MP//LB pot, their only use is to be fused to increase the unit stat/give it limit burst exp.
  -Trust Moogles, they increase the % of Trust Mastery, 5* gives 10% to ANY TM, 4* gives 5% to ANY TM, 3* gives 5% to specific TM.
  
• If you feed pots to an unit, then awaken her, she keeps the pots.
• When you fuse two of the same unit together, their TM% add and you have to add another 5% for each similar unit you fuse.
  
• Most Character get their top notch abilities when they reach their max level.
  
• Max level character still share exp with your other non-maxed unit, only your friend unit won't take the exp.
  
• Most of the material you need to awake an unit can be found in exploration. For Sacred Crystal and Holy Crystal, they can be found respectively in INT Awakening Vortex (until someone run a survey, I won't change it) and ADV Awakening Vortex.
  
• You can't get 6* awakening mats from the pro Awakening Vortex, it only drops mats to awake a unit from 4 to 5 (when this unit had a limit of 4 stars before).

Content:

• We don't know what unit will get 6*, we can just theorize all main protagonist/antagonist will get it.
• New story content get released at the end of each month (approximately).
  
• We can't predict what banner/event will we get next week as GL is not following JP schedule.

Others:

• Colosseum/Arena kill/use of spell or anything do not count toward any quest or trophy.
  
• You get your reward on arena even if you lose.
• Arena Monthly/Weekly reward take a few days to come.
  
• Esper battle count as exploration (toward daily).
  
• If you want to open magical chest in an exploration, you have to bring the keys with you, like you would bring a potion.
• Gift sent to friends aren't taken from you, they appear from a magical dimension, so always use send all.
  
• Macro has been confirmed not bannable by support FOR NOW. Do it at your own risk.
  
• When you use lapis/ticket to pull a unit, the crystal may 'evolve' into a superior rarity, it can go from blue ---> gold ---> rainbow. The unit isn't influenced at all from that, it's just an animation.
  

 
If you just posted a guide and it's not added here, PM me and I'll add it asap.