Through the portal, there is a heavily wounded angel, who is yelling at Tyrael. There's also a wall, off in the distance, which used to have a gate in it but currently does not, as the gate in question is currently lying in splinters on the ground. Demons swarm through the space where the gate once was. The city beyond it is in flames, with angels battling demons in the streets.
The angel continues to berate Tyrael. "The Heavens burn. This is your fault, Tyrael. The Diamond Gates have stood since the light first broke over the High Heavens. Now they lie in ruins. You are the cause." He turns and vanishes in a plume of flame. Tyrael sinks to his knees.
"Diablo did this, not you," Li-Ming says. "You did everything in your power to prevent this."
"Long ago," Tyrael says dully, "my brethren and I voted to decide the fate of humanity. I cast the final vote that spared you from extinction. Now... humanity has birthed the Prime Evil."