Brontosaurus

Brontosaurus excelsus is without a doubt the most popular dinosaur that never existed, with merchandise and television cameos even over 100 years since it has been invalidated. It is a Lightning attributed card made by Clockwork.

Nomen Dubium
This card can not be targetted by Prehistoric cards.

Faux Herds
All other creatures with any sort of Herding ability have those abilities canceled. This creature's maximum HP increases by the combined max HP of all those creatures whose abilities were canceled.

Thunder Crack
A powerful move without a secondary effect.

Origin Information
Discovered two years after the first, juvenile, Apatosaurus ajax, size differences caused its discoverer, Othniel Charles Marsh, to name it as an entirely different genus. A few decades later, a paper was published arguing that Brontosaurus was near enough to Apatosaurus that they should be considered the same genus, with Apatosaurus having priority, making Brontosaurus's valid species Apatosaurus excelsus. Despite this, the skeleton was mounted in the Peabody Museum of National History two years following the paper, labeled as Brontosaurus, which stamped the name so thoroughly into the public conscious that it is still the de facto sauropod for children to love, just as commonly mentioned as Tyrannosaurus or Triceratops.

Using Brontosaurus
Brontosaurus is an excellent counter to any creature with any form of Herding ability, as it negates & benefits from them. It is also very useful support for your own Herding cards, able to boost itself off their maximum HP when they're on their last legs.

Defending against Brontosaurus
As a Lightning attributed card, a surprise Gasosaurus will eradicate Brontosaurus effortlessly. Avoid using any creatures against it that have any Herding abilities, even if you can't activate them. Unlike most sauropods, Brontosaurus lacks any defensive abilities, leaving it a glass cannon of sorts if without any cards to borrow HP from, and therefore making it vulnerable. As with all Nomen Dubium cards, most Prehistoric cards are just dead weight.

Trivia

 * Brontosaurus being made into a card was inspired by the creation of its MMO equivalent, Firebolt Behemoth. Both are powerful cards whose major strength is crippling their main competition, other sauropods.
 * The Faux Herds ability is inspired by how, even in modern times, most people mistakenly believe Brontosaurus to be a real dinosaur.