Perhaps a little insight will help,
" 'Oponn.' The two-faced Jester of Chance " from "The Gardens of the Moon" ( great book by the way ).
I understand the difference between a single jest, and the action of 'jest[ing]', but my question was whether I could use 'jest' in a special ( poetic perhaps ) way to account for all the actions ( related to jesting ) a person has.
As for GG's question, "It never chances I". It never gives me the oportunity to win, it never gives me the chance to come out victorious from Oponn's pranks, chance is not on my side while he is meddling with *my* destiny for his own amusement.
Not sure if I cleared anything with this :P
As for " Damn you, Oponn, how your tune never changes! ", it could be considered similar, think of it as this way, Oponn's tune is refered here as his whole repertoir, every single *song* he plays is similar, it never changes. Thus, you may be referring to an unspecified number of tunes.
Likewise, I am refering to an unspecified number of acts in his jest, but using the singular for all of those as jest.
Tell me if I'm making any sense here 
Also, sorry for any mistakes that might slip in, english is not my main
Thank you