Hello! Quick rules question: can multiple Omens be spent on a single dice action? For example, can I spend an Omen to reduce the DR of a rolled task, and if I fail the task, immediately spend another Omen to re-roll? And if the re-roll fails, assuming I have remaining Omens, can I drop a third Omen on that same task to re-roll yet again? In a releated vein, can a player ally spend an Omen to drop the DR of a task, and then my own character spends an Omen on a re-roll on that same task? Can Omens pile on to a single task so that characters "can't fail" when they really need to succeed? Or is it only "one Omen per turn" for any given task? Thanks!
Rules as written, anyone can spend an Omen at any time to influence the dice. So you can spend multiple Omens back to back to try to pass an essential roll, and you can use an Omen to reroll a friend's failure.
You can also theoretically use Omens to influence the results of roll tables and stuff like that.
Of course, groups can absolutely change this. And individual modules can specify stuff like "you can only use one Omen per test."