In this update article about the mid-season patch for Teamfight Tactics (you can learn about the 3 new units including Vayne, Zed, and Riven HERE), we have learned the first important information such as the champions that have been removed, the new units, and their strengths. However, the new champions from the two clans, Battlecast and Astronaut, have not yet been introduced; we only know about the effects of those clans.

Therefore, Riot Mortdog, the lead designer of Teamfight Tactics, has made a nearly 1-hour long video to explain the upcoming 10.12 patch, as well as to introduce the details of the new champions that will be tested in the 10.12 PBE version. Many unique champions possess incredibly unique abilities that we have never seen in Teamfight Tactics. Specifically:
Champions from the Battlecast clan:
Illaoi: Cost 1 gold, Brawler class

Skill: Illaoi slams a tentacle in a straight line in front, dealing 125/200/325 damage and stealing 15/25/40% Armor and Magic Resist from each target hit for 4 seconds.
Nocturne: Cost 1 gold, Infiltrator class

Skill: Nocturne terrifies the target, stunning them with fear for 2/2.5/4 seconds and dealing 200/250/400 damage over time or until Nocturne is defeated.
Kog’Maw: Cost 2 gold, Gunner class

Skill: For 3 seconds, Kog’Maw gains unlimited attack range, 90% attack speed, and each attack deals an additional 5/7/9% of maximum health as bonus magic damage.
Cassiopeia: Cost 3 gold, Mystic class

Skill: Cassiopeia shoots her claws at the nearest enemy not affected by poison, causing them to take 800/1500/3000 damage over 12 seconds and reducing all shield effects on them by 50%.
Viktor: Cost 4 gold, Sorcerer class

Skill: Viktor burns a line between the two furthest enemies, dealing damage equal to 30/40/100% of their maximum health on the first hit, then after 1 second, dealing a second hit with 250/400/1000 damage.
Urgot: Cost 5 gold, Guardian class

Skill: Urgot fires a harpoon at the furthest enemy in range, pulling them closer and dealing 2000 true damage until that target dies or gets close to him. Upon completing this ability, his maximum energy is reduced by 10/20/60 energy.
New champions from the Astronaut clan
Nautilus: Cost 2 gold, Vanguard class

Skill: Nautilus summons a torpedo to attack the target, knocking them up and stunning them for 3/3.5/4 seconds while dealing 100/200/400 magic damage. Enemies standing next to the knocked-up target are knocked up for half the duration and receive half damage.
Bard: Cost 3 gold, Mystic class

Passive: Bard’s attacks restore 5/20/90 energy.
Active: Bard launches a Meep towards the player’s bench, which can be sold for 1 experience.
Gnar: Cost 4 gold, Brawler class

Skill: Gnar jumps towards a target and transforms into Mega Gnar, throwing nearby enemies and dealing 200/300/1500 damage, stunning them for 2 seconds. While in Mega Gnar form, this champion gains an additional 750/1250/2500 health and 100/175/400 attack damage and becomes a melee champion.
Teemo: Cost 4 gold, Marksman class.

Skill: Teemo throws 3 traps around the nearest enemy. When the enemy steps on them or after 3 seconds, they explode, dealing 175/250/600 damage and severely slowing them for 4 seconds.
New Paragon class
Janna: Cost 5 gold, Star Guardian class

Skill: Janna summons 5 tornadoes that fly forward in a cone. These tornadoes gain 50/100/500% attack speed for 5 seconds when passing through allies, while knocking up and stunning enemies for 1.5 seconds.