Instructions
Attack Ghostfreak while in any of your alien forms. You can't harm Ghostfreak by attacking him directly, so don't be surprised when his life bar doesn't get depleted as you hit him.
Keep hitting Ghostfreak until you knock him to the ground, which stuns him. Look at the background and you will see large golden chains hanging from the ceiling. Each one corresponds to the window curtain next to it.
Transform into Wildvine, then run over to one of the large golden chains and jump up to grab it. This will pull the curtain open on the window and shed light on Ghostfreak, which damages him. If the light misses him, make a mental note of the range of the light beam and make sure Ghostfreak is within that range the next time you stun him.
Keep stunning Ghostfreak and opening the curtain to damage him. Once you've depleted about one-quarter of his life bar, he breaks through the floor.
Align the knight statues so that they reflect the beam of light onto Ghostfreak. He stays huddled in one corner of the room, so you don't have to worry about him attacking you while you move each statue. Once all the statues are aligned, the light hits him and causes a large amount of damage. This also initiates the final phase of the fight.
Attack Ghostfreak with your strongest alien forms. Heatblast or Fourarms are ideal for this portion of the battle, though who you play as is entirely up to you. During this phase, all of your attacks cause damage, so keep hitting him with your strongest attacks until his life bar is fully depleted.