Lithium is a strategically critical yet scarce metal vital for the global energy revolution. Understanding how lithium becomes enriched during orogenesis helps locate lithium-fertile terranes. We investigated seven Barrovian metamorphic sequences and metamorphic country rocks from eleven pegmatite-type lithium deposits/pegmatite fields. Staurolite and biotite are the primary lithium hosts (staurolite > biotite >= chlorite > muscovite) in metapelites, with average lithium contents increasing from distal Barrovian metamorphic rocks (426 ppm and 75 ppm) to those 200-500 meters from evolved granites (738 ppm and 149 ppm), and to metamorphic country rocks within 200 meters of lithium-rich intrusions (1395 ppm and 560 ppm). Integrated whole-rock data and phase equilibrium modelling reveal that staurolite-rich layers with considerable biotite function as natural lithium "sponges", sequestering lithium during metamorphism and fluid metasomatism to form fertile sources for mineralization. These findings establish staurolite-rich terranes, reworked by multistage metamorphism and anatexis, as promising areas for lithium exploration.