Even though the Magic card isn't so great, the art makes it playable.
When found, the Basket of Infinite Snakes is typically closed, and likely covered by a thin coating of dust.
At about 3 feet tall and 2 feet in diameter, the basket appears to be tightly woven, sturdy, and with a removable lid and a pair of handles near the top, just below the lid. It weighs about 10 pounds.
Removing the lid brings the snakes. The lid will not fit back on unless the command word is spoken - fortunately, the command word is on the bottom of the basket, viewable by either upending the basket (and dumping its contents) or by lifting it above one's head - awkward, but easily doable by folks with two arms.
Opening the basket and peering in reveals darkness and the smell of a snake house. Leaving the basket upright and open allows 1d4+1 venomous snakes to crawl out each round until closed.
Turning the basket on its side releases snakes - 3d4 come slithering out each round until sealed. These snakes are venomous and attack anything not snaky. When slain, the snakes disappear. Survivors disappear after 8 hours - just long enough to cause a bit more trouble.
Upending the basket dumps 12 venomous snakes out, as well as the contents of the basket.
Reaching into the basket allows a full dozen venomous snakes to get free attacks on the arm(s). Armor may deflect some, but the fangs punch right through cloth, skin, and the lighter leathers.
A curious byproduct of the magic that created the Basket of Infinite Snakes is that it can hold several hundred pounds without rupturing, similar to a bag of holding. Unlike a bag, though, the basket's volume doesn't become deeper, so the only things that fit are what would fit in a normal basket of this size.
Rupturing or piercing the Basket of Infinite Snakes takes some doing, but a persistent (and/or unlucky) soul can do so. Unfortunately, doing so opens a rift that sucks ALL things not nailed to the floor into the demiplane of snakes. The terrain runs from jungle to desert to ocean - all overrun with snakes. The smell of snake hangs heavy in the air.
Ophidians (snake people) rule this large demiplane, treating mammals as food and slaves.
This rift stays open until sealed, allowing all sorts of snakes to drift through. Ophidians and Yuan-Ti will no doubt thrive, but all other sorts of sentients will likely find their lives brutally cut short.
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Let me know if this makes it into one of your games, either as-is or in some related form. For the record, the Basket of Infinite Snakes rests in my megadungeon, containing some valuable loot and providing a valuable lesson to incautious adventurers.