Grave domain's circle of mortality.

[stoutstien]

While looking for all the sources of THP i realized that circle of mortality isn't worded the same way as other increase/maximize healing effects.
Specifically you don't have to spend a spell slot. So a dream druid or celestial warlock could maximize their bonus action healing. Hardly optimized but just something that could be fun to build around.

[JackPhoenix]

They can't, because Balm of the Summer Court and Healing Light aren't spells.

[stoutstien]

They can't, because Balm of the Summer Court and Healing Light aren't spells.

Crap. There goes my idea for a grave dream druid

[MeeposFire]

Crap. There goes my idea for a grave dream druid

On the plus side since they are not spells you can use the bonus action on celetial warlock to heal and still cast a leveled spell. If it was a spell you could not do that.