Mold-1 is the next boss in Control. Defeat the boss to get a trophy/achievement with the same name. Below you can find a guide on how to find and eliminate this boss.
Where to find the boss?: During Old growth side quest.
Description: This boss can be very problematic. You encounter it at the end of the mold cave, during a side mission for Dr. Underhill. The enemy has various attacks - it can attack with tentacles, throw projectiles at you, use poison gas, and even knock down exploding plants right on you.
You need to dodge a lot and change locations rapidly. Use levitation and quick dodges to move to another spot where there are no toxins and exploding plants. In the meantime, try to use telekinesis to throw various objects at the boss. Try to destroy the "flower" of the boss - this is its weak spot.
However, when you get defeated, you go back to the nearest checkpoint - you will have to go all the way to the boss again.