Kind of that story mode but you can events if u get tired of its story. They just finished season one of the story.

U can use other friends unit to help u in any battle once they accepted your request

Mostly through events. Focus on getting ur units to lvl 100. Equipments on story mode is shait compare to events one or some of the TMR.

What stages are u now? Have summoning lately?

No, unit summon. Go to summon tab and choose standard summon. Choose the free one. Only available for limited times

Try not to use lapis to continue mission. If you lack good units, then summon is a good idea, but probably see what is on the banner before doing so. If you got unit with good TMR, then using lapis to refill energy is not bad too.

Right now, there is a free summon at standard tab, but the unit is actually rare units. It is free once a day for 10 days, starting today. Also, there is a guaranteed 5 stars ticket, claim it from your mailbox. Personally, I would say use it straight away, but it's up to you if you want to use it now or keep for later.

Some people will recommend re-rolling ( keep starting new account until you get what you want ), but it is quite tedious. It give you a head start if you have one good unit, but again quite tedious. I didn't do it, but just letting you know your options.

Regarding equipment, if you have good friend unit, maybe they can help you clear the first trial, that will give you a 82 ATK sword, which is the best non-TMR sword for now.

Oops, sorry.

If you look at a unit page, at the bottom you will see a star, then a  percentage then on the right side, "Trust Master Reward", that's TMR. Story units don't have TMR. Basically, once you get the percentage to 100%, you will get the reward, could be weapon or ability or something. Every battle have 10% chance to increase the TMR by 0.1%, so on average you need 10K battles to get the reward. There are also special units, Trust moogle, that can increase the TMR percentage.

Probably not something you need to worry about now, but it is good to keep that in mind when deciding if you want to keep a unit.

Anyway, what units do you have now?

yes. can read more about TMR here https://exvius.gamepedia.com/Trust_Master_Reward

if you're interested to start all over again, this is how you reroll your account. https://exvius.gamepedia.com/How_to_reroll

Unit rankings. https://exvius.gamepedia.com/Unit_Rankings

Ashe for magic and firion is good for finsher. I say level them up asap and rain can be your tank for now.