Let's say I have two perplexers on my team: any random person with Perplex and Fabian Cortez.

Ok, so, my first perplexer addes +1 to random character's attack. Then Fabian also tries to use Perplex to increase that person's attack value. Now, if I roll a 6 with Fabian, am I not able to use the power because that would make +4 to the same value, which is not allowed? Or is Rule of 3 meaning can't be targeted by more than 3 sources for perplex?

I was just thinking, if this worked, it would be a good fail-safe from getting your target that 1 unavoidable click of damage.

I bealive the 3 is still added and then reduced to a total of 3 instead of 4 and you would still take the 1 damage

Rule of three just means that the stat tops out at +3.

You can still modify the stat, it just won't have any effect. So 6 on the Fabian roll will still do a click of damage.

But of course, the smart thing to do is use Cortez first...

well, ya, I would only do it the othe way around if what I suggested had actually worked....