Bombers are newbloods who can explode objects, including people, by sight. They are more powerful than a Silver oblivion. While oblivions must make physical contact to explode things, a newblood bomber can use their ability with sight alone.
"Bombers are similar to oblivions in that they have the power to explode objects or opponents. Bombers are not limited by the oblivion necessity for touch. Therefore, a bomber can explode something on sight, rather than only that within physical reach." - On Silverblooded Abilities by Victoria Aveyard