Spec Handle: How do I return external Actors that applied a gameplay effect?

[KeelhaulTheLot (BoomerDev)]

I am building a Scape-like game, so I need to be able to return the actor that applied an effect; instead of relying on AI senses to drive NPC aggression.

I am having some major issues wrapping my head around Effect Spec Handles.
I am unsure of how to call one to return the instigator/causer in this EG:

Get Effect Context no longer works in the context pictured. If you need the GetEffectCauser apply GameplayEvent from the attacking actor, and include a payload that includes its self as the Instigator.

See my reply for detailed instructions.

(redirect is there to represent arbitrary code)

[KeelhaulTheLot (BoomerDev)]

Upon some experimentation I have learned that spechandle is partially deprecated due to the deprecation of UE Damage.

The current solution to pass an InstigatorKey is to use a GamePlayEvent.

Actor Sending the Effect:

Actor Receiving the Effect: