I need a trigger to change a unit into another. GUI please

Hi, i was wondering if it was possible to change a peasant into a ghoul in GUI.
I need it to create a map where a plauge turns every one into undead.

Look through the trigger actions before you ask. There's one called Unit - Replace that will probably do exactly what you want.

Oh thanks never noticed that...

You could also use the chaos ability to change the peasant directly into a ghoul. It may be a better choice for you. Do a search on chaos and you'll find numerous posts explaining it.