Captain Rex seems like an incredibly unique and interesting commander to build around, and hey, you dont need to know anything about Attractions in order to run him
Take his first ability which doesnt outright kill an opponent's creature, instead negates most (if not all) damage done by it
Since you're going to attack with (almost) exclusively Assassins, each one will give the others a +1/+0 stat boost
This is potentially the Oko, the Trickster of Streets of New Capenna, justifying its price and its two different positions on this list
To get around this restriction, its a good idea to play backup cards that are functionally similar to your win condition
Its an artifact that might not be that great in constructed or limited play, but is going to be amazing in Group Hug style decks in the Commander format