Existe Símbolo do Sono que é um feitiço que faz exatamente o que você quer. Eu coloquei a descrição aqui e deixei apenas os bits mais importantes.
This spell allows you to scribe a potent rune of power upon a surface. All creatures of 10 HD or less within 60 feet of the symbol of sleep fall into a catatonic slumber for 3d6×10 minutes. Unlike with the sleep spell, sleeping creatures cannot be awakened by nonmagical means before this time expires.
Until it is triggered, the symbol of sleep is inactive (though visible and legible at a distance of 60 feet). To be effective, a symbol of sleep must always be placed in plain sight and in a prominent location. Covering or hiding the rune renders the symbol of sleep ineffective, unless a creature removes the covering, in which case the symbol of sleep works normally.
As a default, a symbol of sleep is triggered whenever a creature does one or more of the following, as you select: looks at the rune; reads the rune; touches the rune; passes over the rune; or passes through a portal bearing the rune. Regardless of the trigger method or methods chosen, a creature more than 60 feet from a symbol of sleep can’t trigger it (even if it meets one or more of the triggering conditions, such as reading the rune). Once the spell is cast, a symbol of sleep’s triggering conditions cannot be changed.
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You can also set special triggering limitations of your own. These can be as simple or elaborate as you desire. Special conditions for triggering a symbol of sleep can be based on a creature’s name, identity, or alignment, but otherwise must be based on observable actions or qualities. Intangibles such as level, class, Hit Dice, and hit points don’t qualify.
When scribing a symbol of sleep, you can specify a password or phrase that prevents a creature using it from triggering the effect. Anyone using the password remains immune to that particular rune’s effects so long as the creature remains within 60 feet of the rune. If the creature leaves the radius and returns later, it must use the password again.
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Note: Magic traps such as symbol of sleep are hard to detect and disable. A rogue (only) can use the Search skill to find a symbol of sleep and Disable Device to thwart it. The DC in each case is 25 + spell level, or 30 for symbol of sleep.
Material Component Mercury and phosphorus, plus powdered diamond and opal with a total value of at least 1,000 gp.
O símbolo pode ser colocado no item, ou em um container em que ele esteja, ou em uma superfície próxima, ou simplesmente como uma medida defensiva para chegar ao item. O símbolo desaparece quando a magia é acionada. Portanto, é apenas para uso único (a menos que você use uma mágica Permanência )