how common are dm-granted special powers?

[King of Nowhere]

it's happened in all my campaign that fulfilling certain plot objectives, or doing something story-wise, grants special mechanical bonuses, often custom/homebrew.

For example, in the current campaign i'm playing, freeing a powerful earth-related entity from imprisonment got each of us a special power. my monk got the ability to wildshape into an earth elemental. the wizard got a damage reduction (stacking with stonkeskin) and a few spells per day. don't remember the other party members' boons. there are many of those trapped entities, and each one gave us boons upons being set free.
when i was DM, i weaved in the worldbuilding that objects associated with heroic deeds may gain special powers. when the party got famous enough, i had it happen to each of them - mostly in ways that would help their shtick, especially to shore players who had a hard time contributing. another time the party was stopping the high priest of vecna from a ritual that was sucking souls to let him ascend to godhood; as the ritual fell out of control, the party got blasted by divine energy, gaining a hefty stat boost and some additional powers. Yet another time, gaining the loialty of an important npc who started out as their enemy, the party gained the chance to train with this npc and get a minor boost to resisting trip attempts (the npc major attack) for free.
So, in my experience, custom rewards are fairly common. You can assume that starting at level 1, you'll reach high level with a few special tricks that are not in the books. perhaps boss npcs can also have some tricks of their own.

And yet, I see almost nobody ever mentioning something like that. And I get a distinct impression that many of the more mechanically oriented forumites loathe everything that is not strictly by the book. On the other hand, it's also possible that nobody discusses those things because they are table-specific, unpredictable, and can't really be counted on when discussing builds or campaigns. it's just a nice little extra that may drop in your lap.

anyway, i'm curious on your experience regarding those kind of plot benefits.

[Mnemius]

I've gamed with two GMs that liked to do that.

One had it themed as divine favor based on deity of character. I just remember playing a VoP druid in his campaign (it was wacky, had people playing satyrs, leonal (I think? cat-person celestial thing)... I hit level 15 and he told me to pick an element to be immune to. I picked fire. Took the wildshape to cold magical beast feat, and promptly entered the next battle as a fire-immune cryohydra...

Another GM, would throw it in as part of story/fun in his eyes. Starfinder, he gave my technowizard character a full on drone (major feature of a seperate class).

And... I'm running some friends through a pathfinder campaign, and part of the big story hook was a boon that threw +2 to a stat of their choice, untyped, on each character. (This is a published adventure)

[Silva Stormrage]

It's fairly common in my experience both as a DM and as a player. I think it tends not to get mentioned in mechanics based discussions because it's hard to actually give advice on. If someone asks how to use a fighter in out of combat scenarios you can't really say "Well a fighter becomes much better in out of combat situations because your DM can give you ability XYZ which solves it". This isn't because the more mechanically focused players hate DM given abilities or think that everything should be by the book but because it's impossible to gauge another forum goer's DM or what they might or might not give to the players. Thus we only have the books to base our advice on.

I am pretty sure though if someone was to post a thread saying "Hey I got XYZ custom ability, how can I best leverage this", you would have plenty of people suggesting options or ways to utilize the ability and no one yelling at the DM for "Ruining D&D" or some other nonsense for giving individual characters custom abilities mid campaign.

[Malphegor]

Pretty common in my group. I don't often get them because I'm usually playing tier 1-2 characters who are already pretty powerful also, my DM's words once 'you know what you're doing', but for martials my DM hands them out pretty quickly.

He's also willing to waive some prerequisites if people ask him for the purposes of fun, which I've never taken advantage of tbh because it entertains me to keep up with such empowered people through sheer RAW effort. "Oh, you have animal companion more like a druid now? Cool. I can lift small ships and chuck them at people." "Oh, you can remain invisible indefinately so long as you don't take any actions? Why didn't you ask me and I'dve made you a magic item of that?" sort of thing.

A lot of it is tbh stuff we could have done with sufficient application of magic and custom magic item crafting or mild tweaks to class features, so it's not like the game is broken tbh.

[radthemad4]

Most of the games I've been in haven't used them, though I'm a fan of the idea. The time I got a domain on a Sorcerer as a reward from a goddess for clearing out one of her temples was an event I remember fondly.

[noce]

In a game I played, the NE rogue helped on his own a very potent NPC, which gave him the ability to stop time for several rounds based on a CON check.

This part of the story was intended for the entire party, and probably each player would have gained a special ability.
Unfortunately, the rogue was played as a selfish, suspicious and opportunist character. Not only we got nothing, but we didn't even know that he got something, or that he was working for that NPC.
Obviously, the rogue used this ability to betray us several times, without us realizing it.

[Psyren]

Pathfinder has a whole system designed for this sort of thing (Mythic.) While it doesn't cover all of your examples, it gives enough of a chassis that you could develop unique powers of your own, like the earth elemental thing. The important thing to keep in mind with this kind of power is that you should always have a plausible means of revoking it in case that is needed to solve any balance problems.

[Biggus]

I mostly tend to do it in the form of unique items when I'm DMing, at least for the powerful abilities. I do tend to give small tweaks to characters for various reasons: for example, I'm currently running a solo campaign, so they got a few changes to make them more survivable on their own.

[ExLibrisMortis]

And yet, I see almost nobody ever mentioning something like that. And I get a distinct impression that many of the more mechanically oriented forumites loathe everything that is not strictly by the book. On the other hand, it's also possible that nobody discusses those things because they are table-specific, unpredictable, and can't really be counted on when discussing builds or campaigns. it's just a nice little extra that may drop in your lap.
It's the latter. Part of the fun of forum optimization is that there's always another trick in the far corner of the one book you didn't check, and someone can find it and beat you (or save your build). The possibility of undefined homebrew change that dynamic entirely, which will ruin the forum optimization game (i.e. change everything, including all the things one might like about it).

Homebrew abilities are like homebrew puzzle pieces: they turn your search-and-match puzzle into a cutting-and-drawing contest. It's not the same thing at all.

[Jay R]

I have no idea how common it is. I've done it occasionally.

In the last AD&D 2e game I ran, the players all grew up in an isolated village in the middle of a haunted forest, and so they had far less information about monsters or the world than usual. To make up for it, I gave them each one 3e starting level Feat.

After a major victory, about a dozen sessions in, I asked each player what their primary weapon was. Then I gave them each a d22. I told them, "Henceforth you can roll this die for that weapon. A roll of 21 or 22 counts as a 'natural 20' by the rules." They seemed to like the special rule. It has a couple of less-than-obvious advantages.

1. It makes very little difference against an enemy who is easy to hit, but a much larger difference for a foe who is hard to hit.
2. It helps martials much more than casters.

[PairO'Dice Lost]

As a DM, I'm not a huge fan of handing out arbitrary DM-granted powers, probably because when I first started playing I ran into some issues with capricious DMs handing out and taking away nebulous magical boons like that. So when handing out homebrew stuff to specific PCs, I prefer to do so in the form of custom items, kind of like Biggus mentioned; sometimes this takes the form of Weapon of Legacy-style items that bind to and grow with the character, other times they're normal items that only the PCs have access to (at least initially) because they e.g. came out of an ancient Netherese vault or were custom-crafted by an artificer buddy or the like.

The one time I've done the "nebulous magical boon" thing was in my last campaign, a Norse-themed one where a person's Wyrd (roughly one's personal destiny chosen by the Norns, the goddesses of fate) and how one adheres to or fights against it was an important theme throughout the campaign. For that, I wrote up a concrete system for how one's Wyrd is tracked, how one gains certain kinds of Wyrd tokens for reaching certain Wyrd thresholds, how one can spend Wyrd tokens to do various magical and/or metagame things, and so on and put it on our campaign wiki ahead of time. While how exactly PCs' actions impacted their Wyrd was tracked secretly through the campaign, once the PCs' Wyrd scores were updated after each session the players knew exactly what they could do with it and it was as "hard" and definitive a mechanic as any printed feat or PrC.

[False God]

On the other hand, it's also possible that nobody discusses those things because they are table-specific, unpredictable, and can't really be counted on when discussing builds or campaigns. it's just a nice little extra that may drop in your lap.

anyway, i'm curious on your experience regarding those kind of plot benefits.

Yeah it's mostly that.

Yeah it happens at my table and when I DM. I think it's a good way to make the game more interesting, especially when a lot of people have pre-planned character concepts, it's a nice way IMO, to throw a wrench into someone's plans, but not in a bad way.

[Aegis013]

I do this type of thing as a DM.

This hasn't happened for me as a D&D player at all. In a different system, where this was simply part of the rules, the GM was so scared of unbalancing the group more than they were, the rewards given out were roughly equivalent of a new cantrip that's worse than those written for a 10th level spellcaster. Often not worth the space they occupied on the character sheet.

[Zekromaster]

And... I'm running some friends through a pathfinder campaign, and part of the big story hook was a boon that threw +2 to a stat of their choice, untyped, on each character. (This is a published adventure)

You're playing Reign of Winter, aren't you?

(Edited because I got my APs mixed up)