Battering Shield

Battering Shield is a heroic tier feat available to characters who are proficient with heavy shields.

When a character with the Battering Shield feat pushes or slides a target with a melee attack while wielding a heavy shield, the character can increase the distance of the push or slide by 1 square.^[PH3:177]

Two Character optimization guides rank this as a good choice for maximizing forced movement, as long as you're using the heavy shield.^{[Char-op fighter]}^{[Char-op warden]}