Conqueror's Crown of Athabasca:

The wielder gains +1 Rulership. Once per session, the wielder may sacrifice a non-summoned domestic unit above half of its maximum HP (rounded up) to automatically cause a hostile spell to fail. The original caster suffers a magical malfunction automatically. Alternatively, the sacrificed unit may instead be used to cast Dispel on a non-hostile spell. (Hostile spells are defined as those intended to harm, damage, or otherwise subdue the wielder or their ruler unit.)