Grentches are mischievous little creatures that serve Grenth in his bid to spoil the joy and spirit of giving on Wintersday. They resemble little green imps and find great joy in destroying gifts and presents before they make it to little children.
Grentches in the Underworld have a projectile attack which uses the same projectile graphics as the Snowball spell, but only does 18 damage at armor 60 characters. This means that, unlike players, they can continue to attack while their skills are disabled.
As of Wintersday 2007 Grentches are able to teleport out of areas where they could be trapped in previous years. (e.g. near the lighthouse).