While Defiance can't do 4 to face that is far less relevant than with creatures where it is all about reaching that toughness threshold
Interestingly, while you can create a copy of a melded creature or planeswalker, tokens that are copies of meld components cannot be used to meld because tokens cannot return to the battlefield once exiled
Its free when your commander is out, which makes it a perfect fit for commanders that hit the field early like Jeska, Thrice Reborn or Rograkh, Son of Rohgahh
Illustrated by: Square Enix
He made some format changes (setting the starting life totals at 40, allowing any legendary creature to be the Commander, creating a banned list, among other things) and was largely responsible for spreading it
Adding blue makes this an especially appealing partner to utilize in the command zone