Keep it simple and make it a coin toss.
Perhaps the skill levels we have could come into play for such events. Set required successes and/or a Threshold Number, and have the ability in skill (Expert, Adept, Novice etc.) change the Threshold Number or the required amount of successes accordingly. This way such events wouldn't have to rely on pure chance.
<Snipped quote by Leidenschaft>
Jaime Lannister hand!
you mirin' for sadri's swag I see