Brave Lyn
Olivia
Fjorm
Fjorm is free 5-star base unit that players get in Book 2. She is a relatively sturdy unit that can tank some hits for your Brave Lyn. In addition to her great tank base skills, she also has Drive Atk 2 which can grants any unit within 2 spaces +3 Atk. This stacks with other Olivia’s Hone Atk giving your Brave Lyn a possible + 7 Atk each turn. Equip your Olivia or Fjorm with a Spur Atk or another Drive Atk seal, and you’re looking at a massive +10 Atk buff.
Gunter
Gunter is another free unit that you can get by completing his Hero Battle. Sporting a decent physical bulk, he can also tank a hit or two for your Brave Lyn. What makes him particularly noteworthy is his Hone Cavalry buff that he gets at 4 stars. This buff alone grants Brave Lyn a whopping +6 Atk and +6 Spd. Coupled with a Drive Atk or Spur Atk Seal, Gunter can be providing +10 Atk and +6 Spd to your star archer just by himself!
If you’re just starting out and looking to put together a team that can clear the Grand Hero Battles’ toughest difficulties, I believe this is the fastest and cheapest way to go about doing it. Brave Lyn is too strong of a unit and with the right support, can be used to cheese most content. Again, her only weakness is the fact that she can’t kill high armor units with the same ease as non-armor units. For those maps, you may just have to dance around a few more turns, but she’ll eventually get the job done.
Images courtesy of Nintendo and Intelligent Systems.