What it is, is a slime that randomly spawns as one of the five elements (fire, cold, poison, energy, physical). It's damage and resistance types are set according to their corresponding element, i.e. a fire elemental slime will have it's fire damage and resistance types set to 100 fire, other damage/resistance types are randomly set from 10 to 35. If it is attacked by spells or weapons that have spell effects on them, they will spawn up to 10 normal slimes.
The elemental daggers they drop have a base damage of 23 to 28, and between 125 and 150 durability. Their damage type is dependent on the type of elemental slime that was killed and have no other stats, which makes a good base for imbuing, or applying weapon attribute deeds or spellcrafting if you use those on your shard.
This is all drag and drop, just drop in your customs folder, reboot shard, and spawn. It was created for a RunUO 2.0 shard, but so far I haven't run into any issues with ServUO up to most recent repo.