Molten Core improve Garr & Golemagg Scripts

Golemagg: 
Magma Splash was not working in my tests, but when its casted on combat start it does. 
Regarding the comment, i think the add despawning on boss death should be handled in DB?

Garr:
Add Enrage cast on Add death

Garr sacrified his adds randomly when he is > 20% health, but i could not find much information on this