Garud Build - Horizon Walker

Scorching Sun Is Her Best Set - The 2-set gives Magic ATK +10% and the 4-set stacks Magic ATK and Heat Boost on every successful attack, which is exactly what she wants: she attacks constantly through Crimson Blaze additional Responses and Blazing Feathers procs, so the 6 stacks fill fast and stay up. Nothing else in the game feeds both Magic ATK and Heat Boost at the same time.

Full Magic ATK Substats - Garud has one of the highest base Intelligence in the game (39 at full raises), and Transcendent adds another Magic ATK +50% on top, so Magic ATK substats convert directly into damage on every source she has: Incinerate, Ignite, Phoenix Feather, Blazing Feathers ticks and Flame procs all scale off Magic ATK.

The Crit DMG Second Build - A Crit DMG build can also be busted: at EX+4 every successful Ignite permanently gives Crit Rate +5% and Crit DMG +10%, stacking up to 10 times. That is up to Crit Rate +50% and Crit DMG +100% by herself by the end of a long fight, so Crit DMG substats turn her into a monster once the stacks are rolling. Run her stigma as a 2+2 split here: The Four Horsemen on Bottom and Right for Crit DMG, Scorching Sun on Top and Left (Top gives Magic ATK, Left gives Heat Boost), which also adds the Scorching Sun Magic ATK +10% and Four Horsemen Crit DMG +20% 2-set bonuses at the same time. The catch: it needs EX+4 and time to stack, so the Magic ATK build stays the safer default.