In the past, this particular dragon held a grudge against Toothless due to some past confrontation that resulted in Toothless leaving a distinctive scar on the Whispering Death's hide where he bit the other dragon, forming a rivalry between the two. The Whispering Death eventually made its way to Berk where it encountered Toothless once again and immediately saw that the Night Fury was grounded due to his tail being damaged. It gained advantage over Toothless due to his inability to fly, striking the Night Fury in the leg with one of its spines. Before it could continue its assault, the Whispering Death was forced to retreat underground when sunlight falls on it.
Hiccup attempted to train the Whispering Death to stop its attack on Toothless, but none of his tactics had any effect on the wild dragon, and Toothless and his rival engaged in another battle. Although Toothless tried to fight it on his own, his inability to fly put him at a disadvantage. The Whispering Death nearly killed Toothless by cornering him into a canyon, but it was only after Toothless accepted Hiccup's help that the wild dragon was overpowered. As Toothless was about to kill the Whispering Death to end their rivalry once and for all, Hiccup stopped Toothless, and the Night Fury allowed the Whispering Death to flee. After it was driven away, the holes it made through its burrowing were blocked up with boulders.
Abilities Strength: Can hold his own battle against toothless easily
Enhance durable : Can take many damage from toothless can continue getting up easily. Also can take a hit on the head of large boulder.
Speed: his speed show to be in the air faster then compare underground.
Agile: it shows to be good at dogging easily toothless plasma blast
Acrobactocs: show to be very flexible body, agility is great going into the ground, and its reflex is great of reacting to things. In the air for flight works better then underground. While underground slither like snake.
Intelligent: Can tell that toothless couldn't fly at all that made him weak to be easy to defeat. Also knowing his digging skills will be useful to surprise his enemy and prey to come out of any where
Fire: can shoot rings of fire multiple times
Spine shot: can shoot any part of his body as multiple of spines can come out
Burrowing: shown to make a lot tunnels being alone at high speed.
Senses: senses of smell shown to be very strong to find toothless also resist of dragon nip that will make itself sneeze and vision shows to be good at seeing in the dark but while the sunlight in the day hurts their eyes.
Fighting style: He shows to be powerful worthy opponent for toothless by using his long body and abilities to use against him and others. He shown great defense that will be useful in battle showing thundrum sonic boom has no effect on him. His looks makes most Vikings be afraid to fight back.
Flight: shown to be good flyer
Weapons: sharp teeth, horn, spines, tail, and head