If you deal lightning ore thunder damage, with a spell roll 1d20. Then activae the effect based on your rolled number.

1 - 5 The ever lost

6 - 12 Better Thunder

12 - 18 True Thunder

18 - 19 Thunderbringer

20 Wrath of the Storm Dragon

The ever lost

Roll the d20 again. If the effect The ever lost is again activated, add 1d6 to your Spells damage.

Better Thunder

Roll 1d4. Then add a number of d6 to your damage roll, based on the rolled number.

True Thunder

Roll 1d8, then resolve one of the following effects, based on the rolled number.

1 - After your spell resolves, you cast a Fireball with you as its center. (The damage typ is lightning ore thunder, your choise.)

2 -  For one minute, you have to scream to communicate.

3 - Choose three creatures that you can see, they take 3d10 thunder damage.

6 - You regaine  a level two, ore lower, spell slot.

7 - Maximize your spells damage.

8 - Activate your channel divinity for free, one your next turn.

Thunderbringer

Cast the used Spell again and if you do, regain the spell slot, and the target can't make a saving throw against the second spell cast.

Wrath of the Storm Dragon

Activate your channel divinity, cast the used Spell again and if you do, regain the spell slot, and the target can't make a saving throw against the second spell cast, ignore all the Resistences and immunities from the target. If the spell hits, roll 1d20. If the Roll is 10 ore higher activate this effect again. If the effect gets activated three times in a row, this ring explodes, and deals 10d10 lightning and 10d10 thunder damage.

Notes: Tempest Kleriker, Warding, Jewelry