The opening, with the Guardians tearing through a Kree warship, also beating Nebula and Ronan before managing to escape while denying the Black Order the gathered Infinity Stones.
Thanos's first appearance when the Time Stone malfunctions depicts him in the future behind the bodies of everyone in the alliance, causing Green Goblin of all people to collapse in a muttering wreck. One hell of an introduction.
Chapter 4 brings us an Ultron-possessed Ultimo marching on Avengers Tower, seemingly unstoppable, only for Hawkeye to pilot in, survive his Quinjet being shot down and landing safely on the helipad, firing an arrow... with Ant-Man riding it, promptly enlarging to Giant-Man and engaging Ultimo in a fistfight, surviving multiple plasma beams to the chest in the process. The heroes then use the anti-air cannons to weaken Ultimo's firewalls, allowing Vision to trap Ultron in the Mind Stone forever.
Chapter 5 has the Sentinels attack the Xavier Mansion, which would normally be considered bad news... Nope! The X-Men are less concerned by the killer robots and more worried about the possibility of Deadpool's tacos being ruined, casually kicking robot ass until Magneto shows up.
Juggernaut, Cyclops and Colossus all engaging Proxima Midnight and Corvus Glaive to allow the heroes to escape with the Power Stone. Even better, Shadow of Doom shows that Cyclops and Colossus managed to outright survive the encounter, meaning Jug probably made it too.
Black Panther quickly dispatching multiple AIM troops all by himself.
Shadow of Doom
Three words: God-Emperor Doom.
How is Marvel’s first family introduced? By saving the heroes from a massive army of killer insects with their awesome powers! A fantastic introduction for the Fantastic Four.
The final shot of the game showing every single playable hero (sans Thanos) together, ready for the imminent battles against the cosmic entities attracted to Earth by the Infinity Stones' power. Eat your heart out, Endgame.
