Even if it was only for himself, it could also have the effect of a life-saving spell!
Take the spell of care as an example.
Considering Matthew had the ability to upgrade spells.
This spell was the effect of a peak Tier 5 spell.
If he suddenly used this spell on himself at a critical moment, in the perception of others, he would be equivalent to turning from an annoying enemy into a disgusting pile of faeces that emitted a strong stench.
Or something even more disgusting!
Under such circumstances, most creatures were unable to resist their instincts.
They would stay far away.
This was just one of the scenarios where the Disgust Spell could be used.
From this, one could see the potential of this spell.
"I heard that there was an evil mage who had been single for many years. In order to take revenge on his love rival who took away the person he liked, he especially went to learn the Disgust Spell.