Kreator frontman Mille Petrozza joined Arch Enemy on stage in Berlin on 19 July 2026 for a guest performance of GBH's punk classic "City Baby Attacked By Rats", with fan-shot footage of the appearance circulating online. The cameo came just days into Arch Enemy's summer 2026 European tour, which is notable as the band's first run of European shows featuring new vocalist Lauren Hart, formerly of Once Human, who took over from longtime singer Alissa White-Gluz late last year.

The tour opened on 17 July at the Area 53 festival in Leoben, Austria, before the band played Bi Nuu in Berlin two days later, where Petrozza made his guest appearance. In a separate interview, Arch Enemy drummer Daniel Erlandsson said fan reaction to Hart's arrival had been "overwhelmingly good," comparing her impact to that of former singer Angela Gossow, and described White-Gluz's exit as a natural end to a long working relationship rather than a sudden split. He added that Hart, a self-described Arch Enemy fan whose favourite album is 2001's "Wages Of Sin", joined at a point when her other band, Once Human, had become largely inactive.