According to op.gg, Swain support is currently tied with Soraka for third highest win rate behind Bard and Janna. While it has a low pick rate, the gain in popularity (this is
Swain Build, Runes, Counters (Top, Season 12.9) - OP.GG - League of Legends
ChampionMastery.GG - League of Legends champion mastery scores for Rework Swain Pls (LAS)
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LoL Swain Counters - Best 12.8.1 Counter Champions & Matchups