From their announcement:
Our new Giant Hill Trolls are truly massive, looming over our other trolls at around 100mm tall. Giant Hill Trolls are gangly, lumbering beasts. The largest stand as tall as a castle wall and are almost as intelligent.
Though slow to act, they are all but unstoppable once they have set their tiny minds on something. Only a brave or foolish warrior will stand in their way. Tasked with such demanding jobs as hurling rocks at people’s heads or launching shrieking Goblins in hang-gliders, a Giant Hill Troll is a valuable asset to any Orc or Goblin warlord who can keep them fed and tolerate the stench.