The Marvel Cinematic Universe (MCU) multiverse cracked open in spectacular fashion on December 15, 2025, when a leaked trailer for Avengers: Doomsday exploded across the internet, igniting a digital wildfire that has consumed social media and dominated headlines. The 2-minute-30-second clip, purportedly from an early assembly cut screened at a private Marvel Studios investor briefing, surfaced on a now-suspended X account before metastasizing to TikTok