How to translate "Facéties de Descendre" from French in the context of a board game?

There is no pun involving "descendre" and "decent"; it is so far fetched as to be sound very dull.

1/ The traditional term is "black humour" (ref. 1) and "dark humor" is a relatively recent synonym (ref. 2).

The Wiktionary (ref. 3) does not list "dark humor" but only "black humor" for which the synonym chosen is "black comedy". However, a distinction is made between "black humour" and "gallows humour"; that latter term is not to be confused as a synonym of "black humour", on the contrary of what is claimed in Wikipedia (see ref. 1).

• Black comedy, also known as black humour, dark humor, dark comedy, morbid humor, or gallows humor, is a style of comedy that makes light of subject matter that is generally considered taboo, particularly subjects that are normally considered serious or painful to discuss.

2/ The basic idea seems to be concerned with a matter of level and that is what the word "descendre" (to descend) implies, a change in the level from a given point to one situated lower. However, "descendre" also has the meaning "bring down by means of a blow", "kill", and as a fight is being talked about in the card one might wonder whether there couldn't be innuendos concerning that. More knowledge about the game is needed. Nevertheless, for a translation near the plain meaning I'd chose "descending" and not "descend": neither "descend pranks" nor "in descend pranks" is correct English.

• Descending pranks

Black humour is the dictionary version (e.g. Cambridge) of humour noir. The link to Wikipedia's article on Black Comedy in LPH's answer gives the origin of the term.

As for "Facéties de Descendre", I'd suggest using a play on the word 'low'. 'Low' usually refers to height, which would tie in with 'descending'. It can also mean 'not honest or unfair', which works well as an adjective to describe a prank or trick.

"Low pranks" would indicate pranks which are unscrupulous or dishonest.

"Low cunning" or "Low trickery" would be slightly more commonplace phrases indicating dishonest deceit in general.

Just for the record, I came to the conclusion that "It's a Prank!" would also be a viable name for the ability. It's not a literal translation by any means, but I believe it fits the theme pretty well.

While both "Descending Pranks" and "Low Pranks" would be closer to the original meaning, I think they don't fit the overall humorous tone of the game as well.