I - Rules
(see JITD, p. 22; FAQ, p. 5)
Enemies adjacent to a figure with the Grapple ability cannot spend any movement points until the figure is dead. They may still attack as normal.
Fly versus Grapple
A figure with Grapple affects flying units. However, it would not affect a soaring figure.
II - References
Heroes with the Grapple ability: none.
Monsters with the Grapple ability: Nagas.
Skills granting the Grapple ability: Bear Tattoo.