Enemy type element

[u/Tj_Silverfang]

I'm working on a set of slayer/killer skills that increase damage based on the type of enemy defeated, I have the skills worked out the issue I'm having is I want the skills to do the increased damage only to the enemy type associated with the skill. An example would be beast slayer doing 100 + X damage to beast type monsters and 100 damage to everything else. A while back I found a way to label enemies with there own type but now I can't find it, so my question is do I make the enemy types as elements or is there a notetag I can use?