Lua Understanding Spell formula

[Seksy]

Ok I have learned a lot in recent weeks. One thing that still eludes me is the understanding of spells formula
setCombatFormula(combat, COMBAT_FORMULA_LEVELMAGIC, -3, -30, -3, 0)
setCombatFormula(combat, COMBAT_FORMULA_SKILL, 0, -20, 0.9, 0)

can anyone step forward and explain the basic concept on this? the numbers?
I have seem some posts but they didn't explain it very well and im searching until im going blind

consider this spell formula for dummies lol

 

[Limos]

https://otland.net/threads/setcombatformula-tutorial.229387/
https://otland.net/threads/spells-damage.159751/#post-1537893