Varus
In all the previous versions of Season 5, Varus has never been buffed by the Teamfight Tactics design team. Instead, this unit has faced numerous nerfs, from the interaction rate with Attack Damage of skills, the damage buff for allies, to basic stats. In fact, in patch 11.13, Varus even received an indirect nerf when the Celestial trait had its armor/magic resistance and skill damage effects reduced. Therefore, at the moment, Varus is showing himself to be an extremely weak champion.

The main reason leading to Varus being continuously nerfed is that the design of this unit has proven to be extremely unbalanced. With long range, strong damage skills, and interaction with both Attack Damage items and skill damage, Varus has shown to be a perfect carry in the mid-game. Not to mention that this champion also receives additional defense stats and skill damage from the Celestial effect. Therefore, Riot had to nerf Varus’s stats so that this unit could not unleash its overwhelming power.
LeBlanc
From the very beginning of Season 5, LeBlanc has proven to be extremely “broken” when synergizing too well with the Blue Buff to continuously stun opponents. After about a week of dominance, LeBlanc faced nerfs such as increased energy lock time and maximum mana in patch 11.9b. In subsequent versions, stats like stun duration and damage of the skill “Chains of Corruption” were continuously nerfed. Riot even reduced LeBlanc’s starting health in patch 11.12.

The annoying point about LeBlanc is that this champion provides strong crowd control continuously when fully equipped with items. Therefore, opponents have very few countermeasures against LeBlanc and often find themselves in a passive position. Not to mention that this unit is an Assassin and possesses a terrifying amount of damage. Clearly, allowing a unit to have both strong damage and good crowd control is unbalanced, so Riot has continuously nerfed LeBlanc in recent times.
Katarina
If you remember the annoying feeling of Talon in Season 4, Katarina at this point is even stronger than that. Instead of having to eliminate opponents, Katarina only needs to cast her skill to teleport around the battlefield and deal damage. Not to mention that Katarina’s skill also inflicts the Grievous Wounds effect and counters well against champions and comps relying on healing like Hecarim, Vladimir, and the Celestial.

Of course, possessing too many effects while still dealing strong damage has made Katarina an incredibly unbalanced unit. Therefore, Riot has continuously nerfed this champion’s skill damage in patches 11.12 and 11.13. Even Katarina’s base health has been reduced, making this unit easier to take down in the early game. Additionally, the reduction of Riot’s basic critical damage has also weakened champions like Katarina, who only relies on Infinity Edge as the sole critical item.