As a reborn God of magic, spells come easier to you than others. Due to this, your proficiency allows you to cast spells using a spell slot one level lower than listed.
For example level 1 spells become cantrips. Level 2 spells require only spending a level 1 spell slot ect.
Cantrips remain as cantrips and this is not an excuse to use "level 10 spells"
Should you have any level.9 spell slots, it just acts as an additional cast of a level 9 spell alongside your level 8s.
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