I stupidly dismantled empirical evidence early in the campaign before I realised I would need it for the attunement quests. I have been desperately grinding throne world, wells spring, strikes, public events, altars etc. I can't get it back through the collections as it was a randomised drop, and can't figure out if I can buy it anywhere. Does anyone know if there is a specific mission, or activity that drops empirical evidence to attune before I pull my hair out!