There are plenty of powerful builds available in Teamfight Tactics, but one of the most broken of them all is the Luden's Echo into Rabadon's Deathcap(x2) build from Reddit. Popular content creator William "Scarra" Le showcased how OP it can be on his stream.
In TFT, Luden's Echo is supposed to grant 20 bonus AP and its passive deals 200 splash damage on hit. Due to a bug with the item, the splash actually deals damage equal to the holder's current total AP. A composition with six sorcerers can exploit this bug to the fullest extent since the buff grants 100% damage increase from spells.
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The goal is to give Luden's to a single unit that's able to spam abilities (in this case, Akali) and then stack two Rabadon's Deathcaps on top of it. Since Deathcap grants 40 AP and has a passive that increases AP by 50%, your unit will output otherworldly levels of damage. You can find all the math for it here.
Riot hasn't said anything about plans to fix the bug yet, but it will likely be addressed around the time Patch 9.14 launches. You'll probably be seeing this a lot in your games until then, so it might be a good idea to have some Dragon's Claws ready so you don't get completely one-shot.