Evaluating Attempts and Outcomes: One thing to remember universally about Resolving Outcomes is that something which seems obvious to a player may in fact call for a check; The GM knows more about all the variables impacting each situation and has the final say. That said, the GM may not be taking into account all things about a character, so it is fair to remind them of a particular capability or condition which may influence an outcome if the player does not feel it was factored in. There is no action “stack”, The game master will determine how near simultaneous and action response/reaction cycles are resolved. Others may have input, but the GM makes the final evaluation.
Is there always a chance? > There is an axiom of “Don’t say no, just determine difficulty.” While this sounds good in practice, it does not take into account the particularly lethal aspects of lethality and lack of any capability or frame of reference in which a character may find themselves. GMs by default adhere to this, but are free to simply say “no” under normal circumstances.
Does the same measure of result, always have the same outcome? > Again, this can be argued for simplicity. However, GMs may also introduce a leveled approach: An extraordinary result with high capability may exceed the result of merely being extraordinarily lucky. In fact, the delivery of a highly capable outcome may border on a perfect vision of elegance and style rather than the miraculous.
EXAMPLE: A character tries to prepare an ambush and rolls an extraordinary outcome for camouflaging themselves on the side of a river. They have no proficiency. The narration may relate to the fact that they’re not able to see themselves while they do it, so it’s get just lucky enough to give them the opportunity that they need. Someone who has capability uses the water’s reflection to make sure that they can’t see themselves. They look at the sun coming through the reeds to make sure the bulk of their form doesn’t look unusual in a shadow that it’s casting. They’re positioned just right to give them upward thrust access right to a vital point as somebody comes by. It’s an extraordinary result, but it should be narrated as a “Yes, And…” rather than just a yes.
You can always just make a decision to facilitate the flavor and direction of the story you wish it to have.
Do not be afraid to alter outcome results to enhance the suspense or heighten the feeling of the experience. You should NEVER set out to kill PCs. All things being equal, you should NEVER alter a check that directly results in killing a PC (though you may fear the ramifications); NPCs are yours to decide what to do with ultimately, to facilitate the story, but it is not recommended. Without the players knowing character death is possible, there is no heightened tension, and it loses the ultimate point of immersion. The GM is NOT the adversary of the players – the GM is the teller of tales, there to ensure the action is interesting, balanced, and fun for everyone in the group (including themselves).
Single Check Outcomes are Lethal: A checked outcome may also be assessed using Advantage or Disadvantage. This speeds up combat and emphasizes skill over luck, and is to be used unless noted in materials. It also rewards tactical planning and forethought in committing to combat because it is more lethal.
Stock Check: Determining whether or not a particular supplier or store has an item a character wants is up to the GM. If the GM needs to introduce an element of randomness, flavor, or risk, the stock check should be used. Their check may be augmented by additional funding, motivation, or game situation the character(s) finds themselves capable of leveraging.
Without having to go through and notate a lot of material, there is some very simple and easy things you can do, on-the-fly as a GM to make combat either more or less challenging to suit the specific PC’s. This is not something that you should just do because you can – there should be good reasons for doing it. Simply trying to make it easier for a group because they made bad decisions leading up to it is not very appropriate. Most often, it will be done universally – i.e. the particular adventure’s challenges are just too strong for the PC’s, but the GM wants to use the story thread, or it was just an inordinate amount of bad luck leading them to be ill-equipped to deal with the challenge at hand.