
State your wish to the DM as precisely as possible.
You might be able to achieve something beyond The Scope of the above examples. You can force the reroll to be made with advantage or disadvantage, and you can choose whether to use the reroll or the original roll. For example, a wish spell could undo an opponent's successful save, a foe's critical hit, or a friend's failed save.
Reality reshapes itself to accommodate the new result.
You undo a single recent event by forcing a reroll of any roll made within the last round (including your last turn). For instance, you could make yourself and all your companions immune to a lich's Life Drain Attack. You grant up to ten creatures you can see immunity to a single spell or other magical Effect for 8 hours. You grant up to ten creatures that you can see Resistance to a damage type you choose. You allow up to twenty creatures that you can see to regain all Hit Points, and you end all Effects on them described in the Greater Restoration spell. The object can be no more than 300 feet in any dimension, and it appears in an unoccupied space you can see on the ground. You create one object of up to 25,000 gp in value that isn't a magic item. Alternatively, you can create one of the following Effects of your choice. You don't need to meet any requirements in that spell, including costly Components. The basic use of this spell is to duplicate any other spell of 8th level or lower. By simply speaking aloud, you can alter the very foundations of reality in accord with your desires. Wish is the mightiest spell a mortal creature can cast.