Leaf Shield is one of Torchwood's abilities in Plants vs. Zombies: Garden Warfare 2. When activated, a ring of leaves will spiral around Torchwood for 15 seconds, allowing him to take 50% less damage. However, this ability will slow him down as a side effect. Either clicking the ability button again, or using Smoldering Madness will cancel this ability.
It shares its name with, and behaves similarly to, the Leaf Shield, the weapon used by Wood Man from Mega Man 2.
Torchwood takes reduced damage as long as he's surrounded by his protective leaves. Be careful though, he'll move much slower!