I repeatedly spawned the mad variant of siren head, and eventually I spawned a version of him that walked faster, and kept shooting a laser at me that killed me instantly. I have a screenshot (https://psteamcommunity.yuanyoumao.com/profiles/76561198041022589/screenshot/%p1%/) but it's from a bad angle. I thought this is probably an easter egg or something the dev added, but I just though I'd share this here.