This typo pertains to 'Molten shield'.
Annie grants herself and Tibbers 16% damage reduction for 3 seconds.
While the shield is active, enemies who basic attack ~it~ take 20 (+0) magic damage.
The typo is 'it' I believe you meant "them", I understand you meant shield but with the previous sentence structure you are negating the inferred topics. You say 'it' but there are multiple possibilities.
Let me know if you agree or like the find :]