Before we talk about build options, we most discuss Kali's Passive, Marked for Death. This passive is very unique when compared to other passives in the game. When you load into the game, or die, a target selection UI will appear, allowing you to pick an enemy to mark for death. This is your target. When you kill your target, or get the assist on your target, you will be healed for 80% of your maximum health, 20% if you get the assist, and gain an additional 30% gold for the kill. Unfortunately for your enemy, that isn't all. You also gain a passive penetration against that enemy, 10% plus an additional 1% per level for a max of 30% flat penetration at level 20. That is 2.5 stacks of an Executioner just for being level 20.

Despite this new found protection reduction your target should NOT be the Warriors of the Solo Lane or the Guardians of the Duo Lane, your best choice is the squishy mage in the Mid Lane. This is simply because of how often you have the chance to gank middle lane. Speed, Red, Mid Camps, everything on the map other than the Blue and Purple buffs are slower to mid than any other point on the map. Learn to communicate and coordinate with your Mid Laner, ask if the enemy has used their escape, ask if beads are up, plan your ganks properly and you will be rewarded in kind.

Simply adding this section to hammer home that you MUST build boots first. Do not finish your mace. Finishing your boots is some of the most cost effective power you can get in the game, as well as increasing your movement speed even further for clearing the Jungle faster. I repeat. Do not neglect your boots.

On another note, do not build Ninja Tabi on Kali. This may seem counter intuitive, considering she is a chain saw character that will later build into Qin's Sais, but we aren't at that point yet. In the early game your Lash will be a large part of your damage to camps and Gods, you just need to trust me on this. Warriors Tabi, not Not Ninja.

Once you've finished boots, Warior Tabi for the love of god, you'll want to move onto Crusher. Crusher has everything that Kali loves in an item: Attack Speed, Penetration, Power, and a nice little DoT (Damage over Time) that works to make the bleed on Lash even nastier. Once Crusher is finished you move into Hastened Katana, one of Kali's bread and butter items, to stick to enemies.

When you blink onto a target, make them Beads your stun and blow their Dash, you can leap onto them yourself and stick to them forever. Outside of peel from teammates, there really is nothing than can be done to pull you off of your target once you have Hastened Katana. This is further exacerbated by having Beads as your second Relic. Using Beads along with your Ultimate makes you 100% CC Immune and Death Immune for 2 seconds, with the death immunity carrying on your an additional second and a half.

Thousand Fold Blade is simply added as an illustration of what your next item will be, place holder for Stone Cutting Sword.

Congratulations on reaching the Late Game, you have now become Death, Destroyer of Worlds. Once Stone Cutting Sword, Qin's Sais, and Executioner have been finished, there is very little that can be done to stop you from killing someone. If you catch someone by themselves in the Jungle or pushing up a lane, they are basically dead. Beads their CC and walk them down.

At this stage of the game, Blink should be your primary form of engagement, jumping is far to risky in team fights and should be saved to chase down that kill or disengage. In sieges, let your frontliners engage the enemy first while you flank, once CC and relics have been forced, the enemy Gods are lambs for the slaughter.

You now have two sets of Beads, an Ultimate that makes in Immune to Death, incredible movement speed and damage, and a passive that restores your health when you kill someone that you choose should die. You shouldn't pick fights 1v5, but in even disadvantageous situations you will find yourself coming out on top. One such example comes from one of my past Kali games:

We were having problems breaking the base due to poor communication and just teammates unwillingness to not dive into enemies by themselves and die. I had recently been picked off in a team fight and was running to a fight happening in the middle lane where my team was trying to hold their own 4v5. They, more or less, lost the fight, but forced Relics and Ultimate out of the enemy, so I saw it as a chance to strike. The game was finished by my Kali killing 4 members of the enemy team, at the cost of my Ultimate, Magi's Cloak, Beads, and Blink, but we rushed the middle Phoenix, toppled it, and won the game. I was able to reset my Health three times in that fight, partially due to luck but also good target coordination. While Kali's Passive does encourage headhunting for newer players, in the late game it provides a compass for who to focus on. Use that compass to lead you to victory.