Master Terry:
Since time is of the essence we must attack them systematically. Now listen carefully!
The Ol Mahum Captain can be found near the Fortress of Resistance in the northeast.
Next you must go to Gludio, which is quite a distance away. I guess it is becoming obvious that these mutations happened simultaneously in several places around the world.
You can find the Turek Orc Warlord at the Orc Barracks in the northern part of Gludio.
You can find the Ant Captain in the Wastelands of Gludio. Try the underground Ant's Nest. You should not attempt this one alone...
And last, the most dangerous of them all... Have you ever seen the so-called Turak bugbears wandering about Gorgon Flower Garden in Giran? Turak bugbear Warriors are their leaders.
Now then, let's get busy. You start your task and I shall follow you soon thereafter.