Hello smart people!

I have a question about re-rolls and fate points. I know that I cannot spent two fate points on the same roll (i.e., I swing at a monster, spend a fate point to re-roll, miss again, and spend another fate point).

But what about situation where we get a re-roll already? So something like a Space Wolf re-rolling perception. First roll failed, re-rolls (which also fails). Can the Space Wolf spend a fate point to re-roll the re-roll?

I would have said yes.

AFAIR it was not stated anywhere in the DW rules , but a similar situation was described in OW Errata - and mechanics of Fate Points use is the same in these games.

OW Errata, p.37:

" Question: Can a Sanctioned Psyker use both Favoured of the Warp and Ultimate Sanction when he rolls on Table 7–2: Psychic Phenomena? In what order do these abilities resolve?
Answer: Yes, a psyker can use both of these abilities to reroll a result on Table 7–2: Psychic Phenomena, and they resolve in the order that he chooses to activate them. Note that he can even spend a Fate Point to re-roll a result after using both of these abilities (although to re-roll the maximum number of times, he would have to use the Fate Point last, as the result of a re-roll from a Fate Point is always final). "

So in your example Space Wolf battle-brother without a helmet and in Solo Mode can 1) re-roll perception due to Wolf Senses 2) if the re-roll failed he can try to trigger a Demeanour (only once per game session!) , 3) even if this re-roll fails - he can use Fate Point. T he result of a re-roll from a Fate Point is always final

I would usually rule no to reroll of reroll but this is more an experience thing in line with other gaming systems. My usual ruling is that players are required to choose what ability grants them a reroll of that die and stick to it for better or worse and that fate points should only be used as last resorts. The problem that rerolls of rerolls causes is that over time you end up in a situation where a player has messed up and does everything to avoid it and cheat fate when they should just man up and take the consequences. It can also bog the game down if that player has to read up and recite X different rules just to avoid it.

GM: "You fail that skill test."

Player: "I use ability A to get a reroll which says that I can reroll this test if I fail."

GM: "Ok fine, use it"

Player: *Fails* "Crap, I use ability B to get another on that since it also says that once a session I can reroll a skill test because of my relic hat"

GM: "Really...? Alright fine..."

Player: *Fails again* "Grr, I spend a fate point to reroll that"

GM: "You are taking the piss at this point..."

Player: *Succeeds* "Clearly the Emperor is on my side!"

Tabletop does prevent reroll of reroll as well, as there are numerous pieces of wargear, rules and equipment which can grant extra retries but the core rules state that the new result stands. So I'm going to go against Jargal on this and say that while nothing explicitly blocks it in the rules, it would be a house rule to consider instead that you can only reroll any result once no matter what combo of abilities you use.

The problem that rerolls of rerolls causes is that over time you end up in a situation where a player has messed up and does everything to avoid it and cheat fate when they should just man up and take the consequences.

Definitely this interpretation has its logic .

And I always forget that Fate Points rules that I use are houserules (spent FP are restored at the beginning of the next adventure , not session - so they are used very rarely, only for the most serious reasons) l argely for the mentioned reason .

Numerous other 40k RPG lines explicitly forbid re-rolling a re-roll (DH2E Core, for example, states: "Sometimes, a special rule can allow a player to re-roll the dice. When this happens, the second result must be used, even if it is worse than the original result" ). The FAQ in the DH2E Errata makes it even more clear:

Question : Can an ability that allows a result to be re-rolled ever be itself re-rolled (page 22)? What if this is the result of using two different abilities, such as a background special rule and a Fate point (page 293)?
Answer : No. A re-roll cannot be re-rolled, and the second result must always be accepted. Note that a player cannot spend multiple Fate points to re-roll the same test multiple times. He can though can spend a Fate point before rolling to gain a bonus on a test, and if needed spend another to re-roll that test (and even spend a third to gain an extra degree of success on that test, if desired).

Now, I realise all the info above is from DH2E, not DW, but we all know the DW Core Rulebook and its copy-paste, thrown-together issues, and honestly, this wouldn't be the first crucial thing to be left out. For what it's worth, the description of the Codex psychic power "Veil of Time" (DW Core, p. 195), which itself grants re-rolls, ends with this line: " Remember that a re-roll may never itself be re-rolled."

I do recall reading somewhere that a reroll can not be rerolled, just my 2 cents. I personally wouldn't allow it.

What about Mentor? First Founding p. 63.-64.?

"granting one of the normal benefits of spending a Fate Point to that character" - I don't think that it somehow allows you to bypass the usual restrictions of Fate Point use. Y ou can't spend two FP to reroll twice .