Caitlyn
It’s not an exaggeration to say that this marksman is the most favored champion by Riot Games, continuously receiving buffs in recent patches. As a result, Caitlyn is currently the strongest 1-cost champion for dealing long-range damage, boasting an extremely long attack range (1130), good attack speed from the Chrono trait, and nearly every skill cast takes down an enemy champion.

Furthermore, in the early game, when opponents have very few ways to counter or quickly approach Caitlyn, this champion can freely shoot and deal damage. If you can secure a 2-star Caitlyn early on, she can carry you all the way to the Stone Golem round, after which you might consider selling her to make room for other units.
Kha’Zix
While Caitlyn is a strong long-range carry, Kha’Zix is an incredibly powerful melee assassin in the early game of Teamfight Tactics. Alongside the special effect of the Assassin class, Kha’Zix also has a skill that fits perfectly for the early game, Taste Their Fear, which can quickly eliminate single targets.

In the early game with only 3-4 units on the board, frontline units typically move forward to attack opponents, thereby isolating the backline units. This is an excellent opportunity for Kha’Zix, who can swiftly clean up the enemy’s backline. Later on, Kha’Zix can still be useful in a Pilot – Assassin or Brawler – Void composition, so don’t rush to sell this champion.
Graves
If there’s any unit that can be the most annoying in the early game, it’s undoubtedly Graves. At this time, when team compositions are not yet clear, most damage comes from basic attacks. However, with Graves’ Smoke Bomb, for a significant duration, enemy champions will receive a miss effect, giving you an edge in damage.

The most annoying part is that the target of this skill is not random; it targets the enemy unit with the highest attack speed. Essentially, with just one ability, Graves can completely disable the enemy’s primary damage dealer, making it extremely easy to secure a victory.
Fiora
There are two main reasons why Fiora becomes an incredibly strong unit in the early game: one is the skill of this champion – Riposte, which is an excellent single-target defensive ability. With immunity to damage for a period and then stunning the enemy, this skill allows Fiora to withstand fights exceptionally well.

Moreover, with the Cybernetic trait becoming notably stronger in the early game, alongside other low-cost units like Leona and Lucian, Fiora is nearly invincible in the initial rounds. With any random item, you will have a unit that possesses both damage and tankiness, along with a bit of crowd control; Fiora has everything a powerful 1-cost unit needs.