Upon upgrade, it deals sequentially more damage. There's no limit to how many times this damage bonus can apply.
The damage increase from an upgrade increases each time (+4,+5,+6..):
|n||n(n+7)/2 + 12|
- Warped Tongs can continually upgrade Searing Blow over the course of a battle, even with other cards in your hand that have not yet been upgraded.
- Weekly Patch 47: Metamorphosis
- Updating VFX for Searing Blow card (now scales with upgrade count).
- Weekly Patch 46: Adrenaline
- Adding VFX for Searing Blow card.