How do I change enemies' stats with plotscripting?
As explained in the Plotscripting Dictionary you use the command set enemy stat (enemy, stat, value). Enemy is the ID number of the enemy whose stat you want to change. Check the Enemy Editor for this. Stat is the name of the stat you want to change. You find it in your HSI file in the form stat:name. And to finish value is the new value for the stat.
For example, if you want to set the HP of enemy 10 to 437, you write:
set enemy stat(10, stat:hp, 437)
Remember that the changes disappear when you quit the game. The easiest place to use this command is therefore right before the battle.
Feel free to combine it with a get item (item, number) command so that the player gets a reward for defeating an enemy stronger than usual.