The stock list is filled with all these cute little synergies which add depth and complexity to the list -- cast two spells per turn, legendary creatures matter, tokens matter -- but Y'shtola is very clear on what she wants to be doing, and that's chaining together high mv noncreature spells, and this deck simply refuses to do that
But Coastal Breach's advantage is the undaunted keyword, making it significantly less expensive to cast than Rift
I believe the restriction of only getting to use instants or sorceries of 3 mana value or less is a good restriction and plays on the youth in which Aang flees
There's a slim chance of the opponent getting an even better card from Chaos Warp's effect, but in most cases, it's worth the risk
It wont trigger if the attacking creature is blocked and then all its blockers are removed from combat
Even has uses in midrange since you often want to rebuy shriekmaw's and what not