I've heard that ruling on reverse attack before, but I disagree. Reverse attack does not say you have left the "avoid attack" step. it just clarifies that the future steps have a different target. You reveal reverse attack in the middle of the avoid attack step, so there is plenty of avoid attack step left to use a defense, mandatory reveal a block, ect. The ruling is that once reverse attack is revealed, you are no longer in the avoid attack step. I feel like I'm hogging the thread to rant on reverse attack though, so I'll stop.
I guess for reverse attack (but not reverse magic), the original attack is the "controller" of the attack so they can do things like use Akiros Favor to mitigate the damage. I can now see how block and nullify are different though. block triggers on any attack, but nullify only triggers on an enemy "attack"(spell thingy)
To clarify you how Reverse Attack works:
Player 1 has an hidden Block/defense/whatever.
Player 2 has an hidden Reverse Attack.
Player 1 attacks Player 2.
In Avoid Attack Step, Player 2 reveal Reverse Attack.
We are still in Avoid Step, but Player 1 can't reveal Block or use defense, because he is not attacked yet, because Reverse Attack make you the target of the attack only in the 2 next steps.
We are now in Step 3. Dice get rolled.
We are now in Step 4. Damage are dealt.
From step 5 everything goes back to normal.