- "Just a small sting and my enemies will fall."
- ―Ezio Auditore, after acquiring the poison darts from Leonardo da Vinci.[src]
Upon meeting Leonardo da Vinci in Rome, he would fashion a dart-firing upgrade for Ezio's Poison Blade, for a price. However, ammunition was shared with the Poison Blade, therefore, upgrading the pouch at a tailor also increased the number of poison darts Ezio could carry.
Additionally, a Fast Poison upgrade could be acquired from a doctor on Tiber Island by collecting several quantities of ingredients. In comparison to its weaker strength, the fast poison affected the target much quicker, killing them in roughly half the amount of time before the upgrade.
Throughout his ventures in Constantinople, Ezio was shown to have improved the poison darts' capabilities, enabling him to aim them at an enemy faster. He also began to use them in conjunction with more than the Poison Blade alone.
As such, it became available as a secondary weapon, compatible with the dagger, Hidden Blade and medium weapons, while the upgrade to Fast Poison was also available for purchase from every doctor in the city.
Later, she came across the Houngan of San Danje, who gifted her another poison for her blowpipe, similar in effect to the Fast Poison upgrade, though other guards would actively engage in combat with those afflicted.
During the American Revolution, the Assassin Connor was able to use small throwing knives coated in a highly toxic poison known as water hemlock, which allowed him a means of silently assassinating his enemies while remaining unseen. Accompanying this, the poison darts were good hunting tools, as many animals were weak to the poison's effect.
The darts had the same effect as the Poison Blade, but were fired from a distance in the same way as the Hidden Gun. They were, however, completely silent, which made them extremely useful during stealth missions. Aiming and firing a dart was an almost flawless motion, similar to that of the crossbow.
The effects of a poison dart occurred immediately after the target was shot:
- First stage: The target stood at their post or walked alongside their group of guards, though they would soon begin to clutch at their chest and struggle to remain standing as the poison's effects set in. None of their fellow guards seemed to notice that something was wrong with the target at first.
- Second stage: The poison began to have serious effects on the target. They began to flail helplessly in a circle, striking anyone who came within their reach. If they had a weapon, they may have drawn it and flailed it around as well. Civilians and guards alike were drawn to this spectacle, making it a perfect distraction, though they kept enough of a distance to not be hit unless surprised.
- Third stage: The target was overcome completely by the poison and fell on the ground, still experiencing the effects caused by the toxin running through their veins. After a short time, the target died, after the poison had sapped away all of their energy.
From a long enough distance, Ezio would not be noticed by guards even if he shot their comrades. However, they would attack him if he was close enough and they noticed him firing the dart. Poisoning guards (especially Seekers with their long weapons) was a good distraction that could hold any nearby guards' attention long enough for bypassing them, and following this, firing a dart at a target from amongst a crowd of civilians would not draw attention, creating an opportunity for a kill whilst blending.
- Firing a poison dart at a horseman would force him to dismount, and the effects would skip to the poison's third stage.
- In the novelization of Assassin's Creed: Brotherhood, the poison darts were thrown by Ezio, and sometimes other Assassins, as opposed to being projectiles fired from his wrist.
- In Assassin's Creed III, the poison dart used the same model as a dagger featured in Assassin's Creed II.