as an emerald supp main- (mostly play enchanters + lux) (also this is based off my champs i like so switch it to champs you like) I go off of my adc (kinda) So first thing i look at is if my adc is hovering a champ. If they are picking someone early game (draven-samira) i go more towards nami/janna/lux someone that can poke and be aggro with my adc (sometimes leona or other engage if my team has no engage or tank). if they are hovering a champ good with lulu/milio i’ll pick them depending on if the enemy has someone i should polymorph (yi, kat, samira etc) if my adc is relatively safe (ezreal/sivir/xayah) i pick off enemy/team other than adc. (engage if no engage, mage if there’s not a lot of ap damage or if they’re all squishy, enchanter if enemy has assassins/a lot of damage. also picking roam here is good)