Only real downside I see is you are locking only one player out of attacking most likely, so far more limited than War Tax, although it does better protection for planeswalkers, this protects not just you but also your non-enchanted opponents, which is a pretty severe downside
These cards are: Beatrix, Loyal General Rosa, Resolute White Mage Ultimecia, Temporal Threat Deadly Embrace Seymour Flux Judgment Bolt Lightning, Security Sergeant Cloud, Planet's Champion Sephiroth, Planet's Heir Xande, Dark Mage Megitek Scythe Ultima Weapon Fortunately, these are also the easiest cards to get
Pair it up with Nim Deathmantle and Ashnods Altar, for example, and you have a recipe for infinite mana and infinite creature tokens
Now, the point of this story isnt to suggest that morph is the next broken mechanic but rather to propose that morph this time around might be stronger than we think it is, perhaps even Standard strong
Just imagine the pain this little bastard would bring to a table
Players who earned 10 wins in the previous pro tour or have enough Adjusted Match Win (AMW) points from the previous season also earn a Pro Tour Qualification