Empowering Ring

When you roll a 20 on your spell attack roll
while wearing this ring, the target takes an extra
1d8 damage of the spells damage type.
Once per long rest, you may use this magical
ring as a bonus action to empower the next spell
you cast this turn, casting it at one level higher
than the spell slot you expend. You may not cast
a spell at a slot level which you do not normally
have access to.
Requires Attunement.