Question MagicSpells, help with ".buff.InvulnerabilitySpell"

I need help with the spell: ".buff.InvulnerabilitySpell"
All my homemade spells works fine,
when i make a ".buff.InvulnerabilitySpell", it all shows, particules, sounds i add, but people can still throw spells at me when using it.

I had seen servers with this spell i think that wont let other players use spells at them when using this spell.

How can i do it?
Please help! :c