Apply effect to attacker when attacked

[skorski]

Is it possible to create an effect that would in turn add a different effect to a different token on hit?

Ex: Token B is electric. If A attacks B, then A would get a shock that damages A and applies a stun effect.

From what I gather, I can't fully automate this, there would have to be some active part on B to apply the dmg/effect when appropriate. Am I right or is there a keyword I'm missing somewhere?

[LordEntrails]

I only am proficient with D&D 5E, and you are right in that ruleset there is no such capability. But you don't say what ruleset, so I can't answer your question definitively.

[skorski]

I am thinking 5e, I was mistakenly thinking that the effect machinery is a core FG feature and not ruleset specific.

[Zacchaeus]

There is no method to do what you want although there could be an extension that does this.

The basis of effects are core based but each ruleset will have a different take on what effects do.

[Ulric]

Take a look the Better Combat Effects extension. I think it will add the effect for you. https://www.fantasygrounds.com/forums/showthread.php?68831-Better-Combat-Effects