No, the Playtest Cards from the Convention Edition Mystery Boosters are not legal in EDH

Advanced Search Sets Random Syntax Aardwolf's Advantage Abandon Reason Aether Chaser Aggression Ahn-Crop Invader Ainok Tracker Akki Coalflinger Akki Underling Akroan Sergeant Alena, Kessig Trapper Alesha, Who Smiles at Death Altac Bloodseeker Ambush Ambush Party Amped Raptor Anaba Bodyguard Ancestors' Aid Ash Zealot Aspect of Manticore Assault Strobe Assault on Osgiliath Assaultron Dominator Barbflare Gremlin Battering Craghorn Belligerent Whiptail Blood Knight Blood Ogre Blood Petal Celebrant Bloodfire Enforcers Bloodhaze Wolverine Bloodmark Mentor Bonehoard Dracosaur Borrowed Hostility Brazen Collector Breeches, Eager Pillager Brutal Deceiver Buccaneer's Bravado Bull-Rush Bruiser Burning Shield Askari Burning-Fist Minotaur Casey Jones, Asphalt Hooligan Cemetery Gatekeeper Chandra's Pyreling Chaos Lord Claws of Valakut Cleaver Riot Combustible Gearhulk Coming In Hot Coordinated Assault Coral Sword Crimson Roc Crowd's Favor Crown of Fury Daring Escape Deer-Dog Defiler of Instinct Dire Fleet Daredevil Dragon Grip Dragon Tyrant Dragonkin Berserker Dragonsoul Knight Dwarven Strike Force Emeritus of Conflict Enslaved Dwarf Fangblade Brigand Fangblade Eviscerator Fault Riders Fearless Pup Fencer's Magemark Fervent Champion Fervent Strike Fiendish Duo

You can have it be a zombie, and when it enters or attacks, you get to draw a bunch of cards, which is exactly what this deck wants to be doing
This rarity has pushed its market value to a staggering $12,500
1 Counter Blitz (Final Fantasy X) Spread Counters Everywhere The best of the Final Fantasy Commander precons, Counter Blitz, as the name implies, is all about putting counters on your creatures
Must be Special Summoned by Tributing 3 monsters and cannot be Special Summoned by other ways