Toothless saves Rhaegal and destroys the Iron Fleet. 

Toothless is on another rescue mission as his friends prevent the most pointless death on Game of Thrones!
While Toothless, Hiccup and some friends are flying with Dany and her dragons, Rhaegal is shot in the chest by a scorpion bolt. Everyone is shocked and spots the Iron Fleet approaching them. Toothless roars at Rhaegal to retreat and forms an attack on the Iron Fleet with his dragon team. Dany and Drogon fly down to attack the boats while Hiccup and Astrid watch in horror. The two pull back when Toothless fires a plasma bolt, destroying a boat. A battle ensues with all dragons attacking the boats. Toothless confronts the leader of the fleet, Euron Greyjoy, who is about to fire a killing bolt to Rhaegal. Toothless intimidates Euron as Dany watches. Euron's fate is left unknown as the screen cuts to black. A year later, Toothless, Hiccup, Dany, and her three dragons soar playfully as Dany nods in pride at Toothless.