It is possible to use a banshee, either wished-for or lured from below the graveyard to the Animated Forest, where by the construction of a room of locked doors you can trap the banshee in the center of the animated forest. The banshee's scream can travel through closed doors and kill the trees who will leave copious loot without leveling up over time. A PC with wax in his/her ears or some other method to achieve deafness can sit outside the doors and collect the loot. The banshee trapped in the center of the room will quickly reach a very high level, so one must take care not to open the doors after the scumming has started.
Like many 'scumming' tactics employed in ADOM version 1.1.1, this is no longer possible in version 1.2.0; animated trees are now immune to the deadly wail[1].