Dragon Frontiers #101/101 Best of Game #8/9 Holon Phantoms #103/110 Paldean Fates #232/91 Neo Destiny #109/105 Expedition Base Set #19/165 Shining Legends #78/73 Team Rocket Returns #99/109 Pokmon Rumble #9/16 Destined Rivals #231/182 Holon Phantoms #100/110 Southern Islands #1/18 Mew is one of the most sought-after Pokemon in the trading card game, with cards spanning multiple sets and generations since the original Base Set in 1998
For a lean budget, a practical plan looks like this
However, with Rhystic Study on your side, you should have no trouble drawing into an answer for whatever new threats are sent your way

Varina Surveillance | Commander | Stephen Johnson Commander (1) 1 Varina, Lich Queen Creatures (17) 1 Aven Wind Guide 1 Cemetery Reaper 1 Death Baron 1 Dimir Informant 1 Dimir Spybug 1 Doom Whisperer 1 Dream Eater 1 Dreamscape Artist 1 Fleshbag Marauder 1 House Guildmage 1 Lord of the Accursed 1 Lord of the Undead 1 Mirror Entity 1 Nightveil Sprite 1 The Scarab God 1 Watcher in the Mist 1 Whisper Agent Instants (17) 1 Cancel 1 Counterspell 1 Cyclonic Rift 1 Memory Lapse 1 Mission Briefing 1 Mortify 1 Mystical Tutor 1 Path to Exile 1 Pongify 1 Price of Fame 1 Rapid Hybridization 1 Return to Dust 1 Sinister Sabotage 1 Swan Song 1 Swords to Plowshares 1 Unexplained Disappearance 1 Vampiric Tutor Sorceries (15) 1 Approach of the Second Sun 1 Army of the Damned 1 Austere Command 1 Deadly Visit 1 Demonic Tutor 1 Dread Summons 1 Fell the Mighty 1 Hour of Reckoning 1 Living Death 1 Living End 1 Mephitic Vapors 1 Notion Rain 1 Solar Tide 1 Twilight's Call 1 Vindicate Enchantments (8) 1 Anointed Procession 1 Cathars' Crusade 1 Endless Ranks of the Dead 1 Enhanced Surveillance 1 Intangible Virtue 1 Liliana's Mastery 1 Reconnaissance 1 Training Grounds Artifacts (7) 1 Azorius Signet 1 Commander's Sphere 1 Dimir Signet 1 Mana Crypt 1 Mind Stone 1 Orzhov Signet 1 Sol Ring Lands (35) 10 Island 10 Plains 10 Swamp 1 Command Tower 1 Drowned Catacomb 1 Glacial Fortress 1 Isolated Chapel 1 Morphic Pool As with any list I throw together, you should view this as a starting point and adjust it to meet your budget and your meta

Hildibrand's adventure fits the requirement, and being an instant means it gets you closer to triggering Y'shtola on other players' turns (Y'shtola triggers on everyone's end step)
While these specific requirements are difficult to meet, doing so will often win you the duel