Spells and curses flashed through the dark night in Storybrooke. Tamara, powerful at last thanks to absorbing the powers of Regina was intent on using Storybrooke to cast magic on the entire world(as the best method of destroying it). However, the Charming family stood resolute against the witch's delusions and with Emma's own powers, chose to face the witch and fight for what belonged to them.
As Jefferson cried over his daughter's corpse, it came to a showdown between Tamara and Emma.
Tamara sneered. "You'll rot like her!" and sent a magic blast at her. Suddenly, a wooden puppet jumped out of nowhere and took the brunt of the blast. The puppet and Emma fell backwards. The puppet got up first and walked in front of the Charming family, shielding them from Tamara.
"It's over. You can't kill me. Any spell you send against me won't work because I am made of the enchanted tree."
Tamara's sneer shifted into a scowl that Regina would've been proud of. "You've gotten in my way one too many times, August."
She blasted fire from her hands at August. Before he would've burnt though, a shield blocked the group from harm. Everyone looked back to see mr. Gold, having come to save them all just in time. With a wave of his hand, Gold exorcised magic from Tamara and evaporated/reabsorbed it altogether. Tamara fell down, limp, her energy completely drained.
Everyone stood still, except August Booth.
"I guess we owe you guys an explanation."

Gold and August took the gang to the real Henry and revealed the nature of the future doppelganger. August explained that in the future, he'd become the Dark One to protect the Charmings but it backfired badly due to the updating nature of the Dark One's Curse. Emma wasn't very talkative. However, soon the group calmed down. Gold disappeared into the night. Henry got three helpings of everything since Tom hadn't been very kind and August spent his time alone in Granny's.

He heard a knock on the door and opened it. "Emma?"
Emma walked in. "So..."
"So?"
"You became the Dark One." she said. August sat down on his bed and Emma sat next to her. "Yeah, I did. Worst mistake I ever did."
Emma tried to soothe August: "Just because it happened there doesn't mean it will happen now. We know what went wrong and we can fix it, just like we always do."
August's voice sounded rough: "It's not that easy, Emma."
"What do you mean? I know you remember, but..."
"I killed you."