Ok so I thought about what I would want in a Swain rework
Passive-Corvid Swarm: Swain keeps a murder of 5 Ravens around him. Every time he auto-attacks, a Raven shortly follows to attack his target, dealing X damage(Scaling each level with an AP scaling) and inflicting Torment on the target, increasing damage by X% from his other attacks for 2.5 seconds. Swain gains one Raven every X seconds.
Q-Swain sends out a swarm of Ravens to attack a target area for 3 seconds. Deals 100% bonus damage to minions, deals AoE damage to minions. If an enemy champion is in the area of the swarm, the Ravens will converge on them. Swain will also launch his Ravens from his passive for a flat X damage towards the champion, and if the enemy champion had a Raven on them already, it'll refresh the duration of the Torment.
W-Nevermove:
Passive-Last hitting an enemy minion gives Swain X mana
Active-Swain marks the ground, which after a delay will snare enemies for X damage and X time. If any champions are caught, and Swain has any remaining Ravens from his passive, a Raven will fly towards that champion, dealing it's damage and applying torment.
E-Swain sends one of his Ravens to watch over an area near swain for 2 minutes, providing a small area of sight around the Raven. If a monster, minion, or enemy champion crosses the Raven, the Raven will peck at them for damage over time, while providing vision of them for 5 seconds to your whole team.
R-Ravenous Flock-1000 range. After a 1.5 second cast time, Swain disperses into a Murder of Ravens, and after another 1.5 seconds they converge into an area, dealing 100/150/200 damage. Swain appears transformed into a Master raven for 10/15/20 seconds, launching ravens to deal damage and to heal himself. During this time, Swains Corvid Swarm remains off cooldown. 140/120/100 Cooldown.
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There. Now he's a master tactician who has to utilize his Ravens correctly in order to win.