The Golem's (and the Power Golem's) attack has a high projectile (rock) size value 8 (not "0.8") and size no energy value 4 (not "0.4"), making the projectile like "a big orb of light".
As in:
<projectile-particle-system>
...
<size value="8" />
<size-no-energy value="4" />
...
</projectile-particle-system>