Thief

Thief is a new gametype, made specifically around the idea that you can't always rely on your build to save you. Basically, the idea is that whatever kills you gets a random item out of your build. There is no guarantee you'll get your item back either. For instance, a Riven dives you with a Black Cleaver and a longsword. She manages to kill you, and you had a fully stacked Rod of Ages and a corruption potion. The game decides to give her the Rod of Ages, and then the turret kills her. The turret then gets a random item, and the item it gets happens to be the Black Cleaver. Now, Riven can sell the Rod of Ages if she wants to, because the item is now one of the items in her build. Fast forward. She tries to dive you again, but this time the tower has extra HP, AD, and armor shred from the Black Cleaver it picked off of her. You manage to kill her under the turret, and the game chooses to give you the longsword she had. As you do so, a Shaco comes into lane and destroys your turret before you have time to react. Shaco then gets the Black Cleaver, because that's the only item the tower had. He then kills you, and gets the longsword, which still leaves you with just the Corrupting potion. Karthus then drops an ultimate that kills the entire enemy team and gets Riven's Rod of Ages, Shaco's Lich Bane, Annie's Rabadon Deathcap, Twitch's Vampiric Scepter, and Sona's Eye of the Equinox, but he already has an Archangel's Staff and a Needlessly Large Rod. All the extra items he got go into a backpack that he can sell from and that can be stolen from, but he can't use any of the items inside the bag, and the items that go into the bag are chosen at random. In this case, the Rabadon Deathcap goes into the bag, which he then promptly takes back to sell, but as he's running away, a spell bolt from a caster minion kills him. That minion gets the Vampiric Scepter from him, which gives the minion lifesteal and extra damage, until something else kills it.