Unstoppable Force, Immovable Object
Charms and supernatural effects often provide effects that succeed without the need for an opposed dice roll. Sometimes, two such effects conflict.
In Exalted, defense has primacy. If an unstoppable force meets an immovable object, the object stays still. An "attack" is an effect that damages or changes the Exalt’s body, mind, spirit or traits. A "defense" is an effect that prevents such an attack. Insofar as the two effects’ descriptions conflict, the defense always wins. For example, when using an unblockable attack against a magical parry that blocks even unblockable attacks, the parry wins. If the defense can parry only blockable attacks, the attack may succeed—the two descriptions do not conflict.
In some cases, neither effect is an attack or defense. Tracking someone isn't an attack, because finding him doesn’t damage or change his body, mind, spirit or traits. Hiding one's tracks isn't an attack, unless it works by directly impairing the tracker's senses. Nor is either effect a defense. Sometimes, both effects are attacks—for example, an Exalt attacked with an strike that always hits might reply with a defensive Combo that always dodges and hurts the attacker on a successful dodge.
In these cases, make an opposed roll between the dice pools that the Charms support, enhance or require. If the appropriate Attribute is unclear in either case, roll (user's Essence + Ability) for both Charms. The Charm associated with the winning roll overrides the Charm associated with the losing roll. Some Charms are especially powerful and add bonus successes to this roll.