Here is how Ambush by Warg Riders, Fight off the Wargs and Hiccup injured his arm goes in Yuna and the Three Kingdoms.
Princess Celestia: Eret, You go on ahead and scout around Berk.
Princess Luna: We'll stay with Isamu, Indy and Anna.
Eret: Very well, Your Majesties. Coming, Shining?
Shining Armor: Right behind you, Eret.
Princess Cadance: Be careful, Shining Armor.
Jaden Yuki: Don't worry, Cadance. They'll be fine.
Brain: Yeah, What could happen?
Scamper: An ambush maybe.
As Eret and Shining Armor started scouting.
Skullcrusher: (growls after smelling danger)
Eret: What is it, Skullcrusher? You got something?
Shining Armor: Something's wrong!
Suddenly, A Warg Riding scout attacked.
Eret: A Warg Riding Scout!
Shining Armor: Watch Out!
Them Derek came and shot the Warg and it's rider with his arrows.
Hiccup: What is it? What's happening?
Eret: Wargs! We're Under Attack!
Valka: Celestia! Luna! Get the Women and Children to safety! Gobber! Let's go!
Princess Celestia: Everyone! Stay Together!
And so, The Battle begins.
Fishlegs: (took down one Warg and it fell on top of him) Flash? Shining Armor? Little Help?
Flash Sentry: Hang on, Fishlegs!
Shining Armor: (use his magic and got him out)
As Hiccup fought off a few Wargs.
Hiccup: (fighting off a few Wargs and one bit him on the left arm) AAAAHHH!!!!
Toothless: (coming to the rescue)
Princess Lilly Sparkle Rose: Hold on, Hiccup! (blasts a few Wargs)
After the Wargs retreated.
Valka: Hiccup! I was starting to worry! Are you alright?
Hiccup: I'll be okay, Mom.
Princess Lilly Sparkle Rose: Hiccup was attacked by a Warg and it bit his arm.
Twilight Sparkle: Ouch!
Britannic: You're going to be alright, Hiccup.
Hiccup: You're a doctor, Duchess Britannic?
Britannic: I was a RMS Britannic after all. (use her magic and healed his arm) That should do it.
Princess Luna: Oh, Yuna. Where could you be?