How do I switch Immortality OFF?

[Ace_V]

It works perfectly!

For any future users of this script, these are the steps I took.

For a battle versus two Imps and a Zombie, with the latter being immortal, I did the Turn 0 event page as mentioned by DerVVulfman, then added several more pages with the following:

Event Page 2 condition: Enemy 1 was at 0% HP
Conditional Branch: [2. Imp] is [Dead] Inflicted
Conditional Branch: Switch [BossImmortal] == OFF
$game_troop.dmg_unaffected(2, false)
Text: The Zombie is now vulnerable!
Control Switches: [BossImmortal] = On
Branch End
Branch End

Then I copied that event page and changed the conditional branch requirements for the second Imp.

Note: I had to use a switch so it wouldn't mention that it was now vulnerable turn after turn.