Paradox

Alters one minor past event, of no more than 3 hours' duration and no more than 1 month back, that the caster personally did or could have influenced - swapping a memorized spell, putting ale rather than oil in the cask, making it the thief who said it rather than him. Something must always be given up. The DM controls how the change propagates, and outcomes are rarely as neat as hoped. DM notes (p. 65): enforce a fair trade; the turbulence carries a 20% chance of attracting a time dimensional or a Guardian.