|(Quick note for those who don't want to read all of this disciption. If you can't give Rebecca Close Guard or Distant Guard a Drive skill like Drive Def or Drive Res works. A defensive spur works too.Spur Def/Res is the best choice though.)
This build makes Rebecca a very good support unit who packs a punch. Any IV can work with Rebecca but Atk is the best one overall for damage with Def,Res, and Spd is best for defence and support. A HP bane is best and safest bane as her HP can easily be patched up with a HP+5 seal, with summoner support, or merging her as it will get rid of the bane.
With Hama Ya's supportive Def/Res drive effect stacked with more defensive drives,spurs,or guards it grant a ton of defense to any allies with her!
To start things off her weapon should be refined to suit your playstyle or her IV's I would refine her weakest defensive stat due to her mostly balanced statline.
Her special is based on her stats and playstyle. If you want her to deal damage up front I would recommend Bonfire,Ignis,Iceberg,or Glacies depending on her higher defensive stat. Moonbow or Luna to deal with tanks. Or a AOE special to help chip oppents health down for herself and her teammates. Blazing is prefered for higher damage and Growing to hit more targets.
Her assist is up to you but harsh command is my favorite but a repositional or a buff skill is amazing too.
Her A skill I use with Fury for extra stats but a bond skill would work better with this build in cases where you can't afford the hp loss. Atk/Spd my favorite but any bond skill would work amazingly on Rebecca!
Her B skill is up to you. I personally use Desperation given how fast she is but a chill or seal skill would be amazing too!
Her C skill is up to choice with what you have and who you're pairing Rebecca with. Distant Guard is best for ranged tanks and Close Guard for physical tanks. If you want to play it safe and give buffs to everyone then go with a defensive drive or if your on a budget a defensive spur is good too.
Her S skill is best with Drive Def or Drive Res but for extra buffs you can go with the spur def/res seal.