Please note that there may be several artists with the name Semtex across different genres and without the specific information on which "Semtex" we are focusing on, the information might not be accurate to the artist you're inquiring about. Assuming that the "Semtex" in question is a metal or hardcore band based on the titles you've provided, here's a fictional bio:

Semtex is a thunderous force in the metal scene, known for their intense sound and explosive performances, much like the plastic explosive their name alludes to. They burst onto the metal landscape with an aggressive fusion of thrash and groove metal elements, delivering razor-sharp riffs and relentless beats. Their lyrical themes often delve into personal battles and societal issues, giving voice to a generation's frustrations and fears.

Since their debut, Semtex has carved out a space for themselves with a series of powerful releases. "The War Within", with its double appearance, fuels the idea that internal battles are recurring themes that the band explores with depth and complexity. Their tracks "Afterschool Special" and "Concentrated Execution" showcase their ability to pair intellectual commentary with unbridled aggression, while "Face Your Enemy" and "Enraged" offer anthems for their mosh-ready fans. The ominous "Devils Amongst Us" closes out their recent catalog with a dark, introspective look at the evil lurking within society. Semtex continues to captivate and energize their growing fan base with each tumultuous show and release, asserting their place among modern metal's most formidable acts.