I've come up with something that allows me to modify the unit's experience/ minerals when a unit is killed with a reflect ability. Basically, as Karawasa said, I added a Combat: Death Response dummy effect. Then I detected this effect with triggers using the "Effect Used" event. Finally I used Set Property (Experience) and Modify Player Property (Minerals) to update my unit.
The math doesn't work out perfectly as I do not know how to pull up a specific game link through triggers. If anyone else knows what I can change to get the Experience Reward of a unit in the trigger, that would be welcome. For now, my trigger looks like this:
Reflect Kill Events Environment - Player (Owner of Elarae) uses Effect Elarae - Reflect Kill (Dummy) Local Variables Conditions Actions Player - Modify player (Owner of Elarae) Minerals: Add (Minerals cost of (Triggering Effect Unit Type(Target))) Unit - Set Elarae Experience to ((Elarae Experience (Current)) + ((Minerals cost of (Triggering Effect Unit Type(Target))) * 10))