Spend this mana only to cast a noncreature spell
Gargos, Vicious Watcher Getting a whopping 4-mana discount is huge , especially since hydras demand tons of mana pumped into their X-costs

Adeline, Resplendent Cathar Adeline, Resplendent Cathar Ainok Strike Leader Akiri, Fearless Voyager Alora, Merry Thief Amazing Alliance Anim Pakal, Thousandth Moon Apothecary White Araa, Heart of the Spider Arboreal Alliance Archnemesis Armasaur Guide Augusta, Dean of Order Banon, the Returners' Leader Bard, Heir of Girion Bast, Panther Goddess Battlesong Berserker Bitter Work Boggart Prankster Bonny Pall, Clearcutter Boosted Sloop Caesar, Legion's Emperor Campsite Cuisine Case of the Trampled Garden Celeborn the Wise Champions from Beyond Chivalric Alliance Chocobo Knights City of the Daleks Clavileo, First of the Blessed Commander Liara Portyr Cool but Rude Cosmic Cube Craig Boone, Novac Guard Cren of the Spider Brood Dalkovan Encampment Daredevil, Man Without Fear Dark Wings Bring Your Downfall Dawnsire, Sunstar Dreadnought Desert Were-Worm Dimir Strandcatcher Director Nick Fury Doom's Time Platform Doors of Durin Dyadrine, Synthesis Amalgam ED-E, Lonesome Eyebot Echoing Assault Eiganjo Dynastorian Endless Foot Assault Escarpment Fortress Family's Favor Far Fortune, End Boss Fearless Swashbuckler Fire Navy Trebuchet Firemane Commando Gallia of the Endless Dance Ghalta and Mavren Gideon, the Oathsworn Gimli's Reckless Might Gloria, the Great Armorer Gossip's Talent Great Gilded Boat Grim Javelineer Guide of Souls Gut, True Soul Zealot Harbin, Vanguard Aviator Haunted Hellride Hazardroot Herbalist Hermes, Overseer of Elpis Hired Claw Hollowmurk Siege Horizon Explorer

The coolest part in playing this deck is when you finally attach with your horde of Wraiths and someone tries to blow out your entire field with any spells, you can always use instants to counter their defense, pumping your Wraiths in the process
For budget-conscious players, Clarabelle effectively replaces the need for more expensive draw-based rares by consolidating your entire card-advantage engine into a single, high-willpower character that is difficult for opponents to remove without a dedicated action card