Its really just further exploring that same false equivalence: that all creatures, or all permanents, are equally valuable
Instead of stating that you can cast the creature once from outside the game, the new rules state, "...you may put it into your hand from outside the game for 3 as a sorcery." Thus, instead of directly casting this creature from the Companion Zone, you first need to pay three generic mana to bring the creature into your hand
Class cards arent legendary so theres nothing stopping you from playing more than one of the same class card at a time
Maskwood Nexus feels a little strange here as a well-oiled zombie deck will almost solely rely on zombies, and it's not worth a spell like this to fix one or two remaining creature types
It should come as no surprise, then, that Dragons are arguably the most popular MTG creature type to build a deck around
Then, for four mana, you can tap it to put a shadow (a creature with shadow can only block or be blocked by creatures with shadow) counter on a creature, which becomes a wraith for as long as it has that counter