Herod’s Treachery is a territory-class enhancement. The special ability is played as: "Place on a Herod. That Herod may use evil Enhancements [use other enhancements] regardless of brigade. You may discard this card to force X Heroes in battle to return to owner's territories."
Let's say on turn 1 I play Herod’s Treachery and place it on a Herod. Then on turn 2, my opponent wants to make a rescue attempt. Now on this second turn, when can I use the second part of the special ability ("You may discard this card to force X Heroes in battle to return to owner's territories"). Specifically, can I use the ability before I present a blocker? In other words, is the following legal?
1. My opponent makes a rescue attempt and presents a hero.
2. I discard Herod’s Treachery from my territory to force the hero in battle to return.
Or similarly, is the following legal?
1. My opponent makes a rescue attempt and presents a hero.
2. I block with a character who does not have Herod's Treachery on him.
3. I discard Herod’s Treachery from my territory to force the hero in battle to return.