Kog'Maw Void Arcanist Longshot 1g

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Kog'Maw is a flexible early game pickup thanks to having access to three traits, helping you stay open. On the battlefield, Caustic Spittle deals magic damage to the target and applies an Armor/MR debuff. It also deals a lesser portion to adjacent enemies. Excellent value for a 1-cost unit.
Lulu Yordle Arcanist 1g

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Lulu's Whimsy ability deals magic damage to her target while forcing them to dance for a short duration. It also bounces to another target to spread some extra damage. CC is always useful, especially when accessible right from the start.
Neeko Ixtal Arcanist Defender 2g

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Neeko Shields herself before leaping towards her target, then slams down to deal magic damage and apply Chill to enemies within range. She's a relatively simple frontliner overall, but having three traits gives you more potential pathways to work towards.
Ahri Ionia Arcanist 3g

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Ahri is a 3-cost Ionia caster that excels in longer fights. Her Fox-Fire ability sends three flames towards her target, each dealing magic damage. While this may sound underwhelming, every third cast increases the flame count to nine, and splits them between up to two nearby enemies.
Additionally, if there are enemies close by, Ahri will also dash away on cast. This added mobility should aid her survival, and hopefully give her the chance to truly shine. She's definitely got potential.
Lux Demacia Arcanist 4g

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Lux's Final Spark fires a ball of light at the largest group of enemies, dealing damage and Rooting the first two hit. Afterwards, she follows it up with a beam, greatly hurting those initially hit, while still dealing a lesser amount to others within range.
She seems like a decent caster with both CC and burst damage, but may not be able to benefit from both traits at once. Demacia and Arcanist isn't the greatest of pairs.
Swain Noxus Arcanist Juggernaut 4g

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Swain has a lot going for him. As a 4-cost unit with three traits he's already off to a good start, but what makes him strong is his passive ability.
By default, Swain heals every second while simultaneously dealing magic damage to nearby enemies. Combined with his trait, this makes him a tanky and offensive threat.
On top of that, once Nevermove is cast, he aims his demonic eye on the largest cluster of foes, dealing damage and Stunning them. AoE Stuns can be a game changer, so I very much expect Swain to make an impact.
Veigar Yordle Arcanist 4g

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Veigar passively gains increased Ability Power from all sources, making him a great unit to invest items into. Unlocking him requires obtaining two Deathcaps, so this naturally goes hand in hand.
Once acquired, it's his Dark Storm ability that truly brings him to life. This summons a storm of meteors across the battlefield, each dealing magic damage and having the innate ability to (possibly) Crit. Best of all, for each meteor kill, Veigar gains permanent AP.
While it'll certainly take some time to get him up to speed, Veigar could grow into a late game menace after enough scaling.
Annie Dark Child Arcanist 5g

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Annie's unique Dark Child trait allows her to summon Tibbers onto your bench, granting you an entirely separate unit who can be equipped and fielded. A very fun and thematic addition.
As for her active ability, Annie's Enraged Inferno erupts the entire battlefield, Burning and Wounding enemies permanently as they take damage over time. While she may not have synergies outside of Arcanist, Annie is certainly ready to make a splash.
Sylas Chainbreaker Arcanist Defender 7g

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Sylas alternates between three different spells themed off of Jarvan (Cataclysm), Garen (Demacian Justice), and Lux (Final Spark). While he can't use the same ability twice in a row, it's said he will select the best choice for the situation.
Cataclysm leaps at a nearby foe, Stunning them and dealing magic damage to enemies in the radius. Demacian Justice strikes the target with a large blow, executing them if their max Health is low enough. Final Spark has him Shield himself before firing in a line.
Assuming the AI can hold up their part of the bargain, Sylas definitely has a flexible range of powerful feats. As a 7-cost unit, this should be expected, but we'll have to see if the reward justifies the effort.
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