How do you use red bricks in LEGO Batman: Legacy of the Dark Knight?
Red bricks are color/skin variants for suits and vehicles. Activate them from the Bat-Mite Shop menu in the Batcave once unlocked.
Unlike older LEGO games where red bricks unlock gameplay cheats, in Legacy of the Dark Knight they unlock cosmetic color/skin themes that can be applied to any unlocked suit or vehicle (e.g. Ninja, Nautical, Filthy Rich, Toxic Waste, Feline, Gothic, Clown, GCPD, Festive). Activate or toggle them at the Bat-Mite Shop terminal in the Batcave. There is no stud-multiplier red brick — stud multipliers in this game come from the skill tree and gameplay upgrades, not red bricks.