His special ability allows him to use Roll for Damage every 7 seconds, 2 seconds faster than the usual cooldown for the ability.
Sherman may be named after General Sherman, a giant sequoia tree located in California known for being the largest known living single-stem tree on Earth.
He may have gotten this name due to Oak being the largest playable plant in the game, hence being named after one of the largest known trees currently living.
It is advised you deal as much damage to Sherman as possible. Though his Acorns can heal him, defeating the Acorns will only cause more to spawn and try to ride on top of him, helping Sherman in battle. This being said, the large wave of Acorns can help you earn a lot of XP.