space marine, Horus Heresy, Warhammer 40k, power armor, bolter rifle, chainsword, grimdark aesthetic, battle stance, legion insignia, ceramite plating, gothic architecture, war-torn battlefield, smoldering ruins, dystopian future, colossal titan, mechanicus constructs, ornate detailing, baroque embellishments, crimson cape, skull motifs, imperial eagle, warp energy, psychic lightning, dramatic shadows, dynamic angle, fire and smoke, ash-filled sky, hazy atmosphere, desolate landscape, harsh lighting, epic scale, wide shot, high contrast, detailed texture, metallic sheen.