HR isn't such a useless stat as some people believe. Tho, it's ridiculously insufficient so additionally to HR, %HR should be introduced.
Introducing chocolate elemental gems could produce gems with HR and %HR and the table used to modify them would also be able to reintroduce HR on all gems.
Empowered gems could be compatible with big bosses in delves, and be like -
Cavity: applies decay on enemy.
Sticky floor: lock boss/enemies on spot and slow its attack speed
Candycoat: Makes foe easy to shatter, Breaks enemy's defense.

Introduce the Candoria takeover storyboard, where new U10 candified, and alienified biomes will appear.
Pirate Sam from the Sam from the future storyboard would have his own biome and try to use the water element to remove cavity and candycoating from fae, neon, medieval, and geode topside.

The Adventure world creatures are coming out the delve's exit, in that scenario I suggest.

#JackNicholsonForCandoriaOverlord - Making a voice acted boss, like in S O T, would be really entertaining. Maybe get in touch with Rare so you can borrow a tad bit of epicness.

And behind the candoria overlord, Cthulhu.

Tho, for a nice health regen to work and be useful, you need %HR, so the bar actually do move nicely.

I'm telling ya, best storyboard.

Hire me fore more.