A close up of a warhammer with a gun in front of a dark sky

high-quality digital painting,sci-fi,warhammer 40k,ultramarines,grimdark aesthetic,detailed power armor,large-scale battles,explosions and gunfire,ruthless Space Marines,alien enemies,tactical warfare,iconic insignia,heavy bolter fire,glowing energy weapons,post-apocalyptic landscapes,sinister atmosphere,violence and brutality,bullet casings and debris,shattered buildings and ruins,skulls and bones,blood splatters,war-torn cities,dark and moody lighting,powerful warlord commanding troops,heroic sacrifices and bravery,epic battles,desperate fight for survival,empire in the stars,colossal war machines,warriors of the Imperium,chaotic battles between factions.