|Standard Brave build which focuses on maximizing player phase attack. For starters, the build chooses a +Atk boon although +Spd is perfectly fine as well. -Def is the bane of choice because he is already weak in Def, and if keeping his default Def Ploy 3, we do not want to hurt his Res.
For his assist, positioning skills like Draw Back and Reposition are recommended.
For his special, like most Brave builds, we want a 3-charge skill. Luna is the best option for Gaius. Iceberg is a decent alternative as well since his Res will give him an additional 14 damage, but this will depend on whether you go Death Blow 3 or Life and Death 3.
On his A passive, Death Blow 3 is the most consistent and highest Atk giving passive available and is the recommended passive to take. Life and Death 3 is also an option with the additional Spd picking up a few more wins in some scenarios, but the Res decrease means this locks you into Luna and also means it's recommended to replace his Def Ploy 3 with a non-Res reliant passive.
His B passive is fairly flexible. Specific breakers like Swordbreaker 3 can help quad and take out a specific subset of heroes, or he can run Cancel Affinity if TA Raven users are an issue. This should be chosen based on what a player needs on their team and what resources are available.
Gaius comes with Def Ploy 3 as his C-passive, and while his Res may not be sky high, it is solid enough to whittle down physically bulky enemies with lower Res stats. Otherwise, any other team buff a player feels would be beneficial would work here.
For his seal, take Attack +3 for the additional attack boost.