So, I've been working out some documentation that would specify exactly which steps are taken for the various actions and triggers which occur in the Sentinels of the Multiverse game. It might be handy to eventually put this in some Wiki form. I created this initial document based on the rules, some logic that the Greater Than Games staff have stated, and based on how some official rulings have been made.
mechanical order of events.
Hero Turn:
E: Until start of turn.
E: At start of turn.
P: Play card phase.
P: Power phase.
P: Draw card phase.
E: At end of turn.
E: Until end of turn.
Villain/Environment turn:
E: Until start of turn.
E: At start of turn.
P: Play card phase.
E: At end of turn.
E: Until end of turn.
Play card/put card into play:
E: Would play card/put card into play.
Card resolves.
E: Is played/enters play.
(Note: play card ⊂ enters play)
Power usage:
E: Hero would use a power.
Power resolves.
E: Hero uses a power.
Card draw:
E: Player would draw a card.
Player takes card into hand.
E: Player draws a card
Card destruction:
E: Card would be destroyed.
Card is placed in appropriate trash.
E: Card is destroyed.
Source deals target damage:
E: Source would deal target damage.
E: Source deals target damage.
E: Target would be dealt damage.
Target takes damage.
E: Target is dealt damage.
E: Source has dealt damage.
When an action is created, it is wrapped as a single action queue and placed on top of the action stack. Only one action stack exists. When an action occurs, it is placed on the top of the stack, and, if that action, or a reaction to a trigger of that action occurs, the new action is placed on top of the current action on the stack. (If that action in turn causes other actions to occur, they are placed on top of that action in the stack.) Once the topmost action is complete, it is taken off of the stack, and the next topmost action continues where it left off.
Cards which specifically react to themselves being played or entering play (e.g. Heroic Interception or Matriarch's fowls) resolve before other cards which react to a card being played, even though they were played last in card order.
All regular triggers appear to take place after it's corresponding action. Almost all regular triggers have a correpsonding "would" trigger which occurs prior to the action. All reactions which react to a "would" trigger typically have either an 'instead" action or an "also" action. An "instead" action immediately cancels the action about to take place, as well as any further triggers that action contains, and proceeds with the specified action. An "also" adds the specified action to the current action's action queue. The original action is completely resolved, including all triggers, (but not any other actions further up the action stack), and then resolves the next action.
A quick explanation of couple terms. A stack can be thought of as like a stack of plates (or even a stack of cards). The first thing put in the stack is on bottom, with the last thing put in the stack on top. The item on top is always dealt with first, and, when removed, the second to last thing is now dealt with. The first thing put on the stack remains on the stack until everything is completely dealt with such as it is now the only thing on the stack. A queue is like a line (i.e. a grociery store line). The first thing in the line is the first thing dealt with. Anything added to the queue gets put in back and waits for the first one to finish. Once the first is finished, the second is ready to be dealt with. The last item added to a queue remains until all other items are dealt with, leaving it the only one left in the queue.