Ascended Heroes literally is the biggest Pokemon set of all time in terms of pure cards included a whopping 295
Level two is a neat addition, but it's level three that really stands out to me
Its naturally weaker in 1v1 formats, as boards usually wont have 13 creatures on them, so cards like Damnation become better options
But all the scary stuff does have some sort of answer so you arent just going to be able to ride one threat to victory for the whole game

Advanced Search Sets Random Syntax Abzan Beastmaster Abzan Devotee Aerie Bowmasters Affa Guard Hound Ainok Artillerist Ainok Bond-Kin Ainok Guide Ainok Strike Leader Ainok Survivalist Ainok Tracker Ainok Wayfarer Akoum Hellhound Akroan Mastiff Alpine Watchdog Arbor Adherent Arcbound Tracker Ashmouth Hound B-I-N-G-O Banehound Bayou Groff Blazing Hellhound Blink Dog Blood Hound Bolt Hound Boros Mastiff Burnished Dunestomper Carnival Barker Cathar's Companion Caustic Hound Chakram Retriever Champion of Arashin Chandra's Magmutt Chrome Companion Codecracker Hound Cogwork Tracker Corpse Cur Deer-Dog Defacing Duskmage District Mascot Dogmeat, Ever Loyal Dreadhound Dross Ripper Edgewall Pack Eel-Hounds Elven Warhounds Encampment Keeper Enduring Courage Equilibrium Adept Faithful Watchdog Fiery Hellhound Filthy Cur Floodhound Fortress Kin-Guard Gate Hound Generous Pup Ghost Hounds Goldhound Gore Vassal Greater Mossdog Greater Tanuki Guard Dogs Hell Mongrel Hellfire Mongrel Hollow Dogs Hollowborn Barghest Hound of Griselbrand Hound of the Farbogs Hydradoodle Igneous Cur Immolating Souleater Interceptor, Shadow's Hound Iron Mastiff

The Mythic Rare turtle is played in Standard, along with formats like Pioneer and Commander