Quote Originally Posted by DonEsteban View Post
Do you know of any mechanic in any system to "fast-forward" random encounters? What I mean is a mechanic to determine the outcomes of a series of random encounters (or other long-term activity) without actually playing it out. Somewhat like this:

- The PCs are traveling a long distance/exploring a large dungeon.
- A lot of random encounters (rather low level and potentially boring, but necessary in terms of immersion) should happen, so
- the DM determines which encounters take place and presents them one by one.
- The players decide how to deal with them on an abstract level.
- Roll a few dice.
- PCs pay the "costs" in terms of resources, which could be any of hit points, gold, spell slots, magic item charges etc.
- Repeat
This isn't what you asked for (at all), but have you considered just jumping forward and starting the PC's in media res?
Have them arrive at the place at the beginning of a session. They should be tired (on the verge of fatigue), wounded, running, and constantly looking over their shoulder (so they haven't healed in case they have a wand of healing). The Wizard has spent most of his high level slots, the Fighter is bleeding, the Cleric poisoned etc.

This works especially well for travelling long distance, where the travel itself (if played to the bone) will take a bunch of sessions and level up the players over and over before coming to the next "plot point". I'm normally not a fan of the DM-monologue, but describing for two minutes what they see and meet (if required for Plot and Immersion) is indeed preferable to playing it all out. Even a "fastforward" as described by you would take quite a bit of time (I see you still have quite a bit of rolls there, and decision-making tends to be a nice factor in encounter-time too) and lifting it to abstract decisionmaking is probably more immersion-breaking than a good tale that lasts two minutes.

Of course, announce to the players at the start of the session that you'll be talking for a few minutes, but that after that, they're completely free to do what they want once more.

Alternatively, don't roll at all, but do give them choices for each encounter ( a)fight, b)diplo, c) run away ) and write down secret repercussions for every choice. Takes less time, and allows you to quickly add up the "cost" of the enounters they have had underway. Skipping to the plot-relevant action is -not- immersion-breaking and doesn't break player-agency as long as you don't go into too many specifics.