My discussion of the GM’s purpose starts with these three points:

Be the person who canonises and maintains the facts of the fictional world.

Be a fan of the PCs – that is, make decisions (rules-wise and others) that put the PCs in the front and allow them to do ‘their thing’, whether it’s succeeding or failing. As long as it’s glorious.

Pace.

Most other things can be shared, including guiding the game and creating the experience.

One of the things I like best about the Test (and Support) mechanics of Savage Worlds, is that they are obviously designed to allow this, to help the GM arbitrate how to use the rules in a way that corroborates very well with player ingenuity. Whenever a player says “I wanna do [something that makes me go, ‘wait, what, how’]!”, my mind goes through this: Is this against someone? It’s probably a Test. Is it to directly help someone? It’s Support. Is it just some action? Figure out what modifier to give, if any, then roll.

Also Syn are apparently bastards, which is probably the most obvious thing about this world ever since page 1, where we called them Syn – but now it’s time to start and show what kind of bastards, and perhaps, why.

How come Muna lives

Everything Dr. Pikenheinmer said is exactly correct: She simply held her breath, just like with a desync (getting a Critical Failure on your Crystal Channeling roll, in which case your Crystal stops working as a heart and you begin suffocating). It’s also true that powers should immediately stop the moment a Crystal stops working as your heart, whether if through a desync, or because it’s literally ripped out of your chest.

Wanna play in the world of Crystal Heart?