That ETB will lock/unlock a Room or recur an enchantment to your hand to recast it then eerie to make 3/1 flyers
And if your creatures hit, youll get to draw cards plus any other bonus you get from your saboteurs getting in
This bird of death works the absolute best when you have some blink abilities from cards like Kaito, Dancing Shadow or Yorion, Sky Nomad
The flavor text being "I normally charge for my merc services, but I can't just say no to someone who controls their commander." Another card is literally entitled Trading Card "so you dont forget," and gives you the ability to exchange its text box with that of another creature
This cards supreme utility and power cannot be overstated, and to top it all off, its got prowess, so it gets a +1/+1 power and toughness boost (actually +2/+2 because its a triggered ability) whenever you cast an instant or sorcery spell
This does imply that an underwater merfolk city called Atlantis does exist in Dominaria, though