The most effective core build for Sett in Patch 16.2.1 is Black Cleaver into Stridebreaker followed by Overlord's Bloodmail, which achieves a 58.3% win rate. Alternatively, a popular build featuring Stridebreaker, Overlord's Bloodmail, and Sterak's Gage is also very successful with a 57.2% win rate. You should always start with Doran's Blade and Health Potion, and typically complete Plated Steelcaps as your boots.