Caitlyn Piltover Longshot 1g

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Caitlyn's Ace in the Hole shoots a bullet towards the farthest enemy, dealing physical damage to the first foe hit. If they die, excess damage ricochets to the next enemy. A basic unit overall, but a 1-cost Longshot if you need it.
Kog'Maw Void Arcanist Longshot 1g

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Kog'Maw provides excellent value as a 1-cost unit, applying an Armor/MR reduction effect to enemies hit by Caustic Spittle. It's a great boost to your team's overall damage output, and with three traits you get so much more.
Teemo Yordle Longshot 2g

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Teemo shoots Toxic Darts at the nearest unpoisoned enemy, dealing magic damage to them and poisoning them (doing more damage over time). He also shares two traits with Ziggs, providing more synergies later on.
Vayne Demacia Longshot 3g

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Vayne's advantage as an AD carry is her ability to deal true damage. Tumble moves her to a nearby hex, then empowers her next bolt.
Assuming she can stay well positioned, the Longshot bonus goes nicely with the true damage, allowing her to help break through tanks. She's certainly got carry potential in the right comp.
Kai'Sa Assimilator Void Longshot 4g

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Kai'Sa has a fairly steep unlock condition as a 4-cost, requiring you to reach level 8 while arming a Longshot with three items. With Kog'Maw in Void, this could make sense, and in exchange, you're rewarded with a mobile AD carry.
Icathian Rain lets her dash away from enemies before firing a ton of missiles towards them, each dealing physical damage. This could be quite strong if she's equipped properly, and chances are, you'll already have the items to pass on over.
Ziggs Zaun Yordle Longshot 5g

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Ziggs throws bouncing bombs as his regular attacks, dealing AoE magic damage to enemies hit. As for his active, Mega Inferno Bomb causes a huge explosion at the largest group of enemies, dealing proportional damage depending on their distance from the center.
Overall, Ziggs is a pretty stock standard AP carry, but is essentially free later on in the game, if you're planning to level up to 9 (and have a Yordle/Zaunite with 3 items).
While nothing special, he at least fills in the board once you get there.
Thanks for reading! If you want to try and come up with your own team comps for Set 16, check out our Team Builder. For a full overview on the new set, check out our TFT Set 16 Reveal Page.