If you destroy two or more altars in one run, Kali will curse you by shackling a debilitating Ball and Chain to your leg, which will remain with you until destroyed.
If you let it drag behind you, the ball and chain will slow your movement speed. Attempting to fly using a Jetpack with a ball and chain shackled to you will only allow you to hover at the maximum length of the chain, but it's possible to fly if you hold the ball and chain in your arms, this will slow you down horizontally, but vertical speed will remain as usual
The ball can also be thrown at enemies, but it doesn't have much range; it is, after all, tethered to you.
It's possible for the ball and chain to trap you in such a way that you can't escape, so be careful not to let the ball get into places it can't be unhooked from while traversing unusual terrain.
The Ball and Chain will break blocks if it's above the height of the player. This is a failsafe that was implemented to reduce the risk of the player getting stuck, but it can also be used to get gems from the walls or destroy the whole City of Gold.
It has been confirmed that the Ball and Chain can be used to destroy the Moai Head in the Ice Caves. This allows the player to carry a held item into subsequent levels, which was otherwise not possible, and thus being one of the few ways to complete a solo eggplant run. While the Ball and Chain can break almost every block in the game, it's not possible to break the platform of the Alien Queen, Push Blocks or other moveable blocks.
If the player has the Pitcher's Mitt and throws the Ball and Chain upward, the Ball will float and carry the player into the air until it falls, allowing the player to 'fly' and reach higher places that can't normally be reached. However, this can get the ball stuck in awkward places if done wrongly, or damage the player when the ball starts falling again.
Destroying the Ball and Chain can be achieved in the following ways:
- Crushing it (Push Block, Shield, Crush Trap, Loose Platform, etc).
- Sinking the ball into Lava (won't work if it can't fully sink).
- Throwing the ball into The Abyss.
- Making The Worm swallow the ball.
- Spamming the Teleporter.
Spelunky's ball and chain is most likely a reference to Nethack, where a ball and chain can be received by reading a scroll of punishment or potentially by angering your god; it drags along behind you and hits you in the head when going down stairs, but can be picked up and used as a (very heavy) weapon, or thrown to drag you along with it. However, in Nethack there is a plethora of ways to remove the punishment.