In addition to the existing Capstones as is,
It would be nice if they both offered the ability to summon "Nature's Champion" - a CR:20 Nature's Ally.
- It would be even nicer if this stacked with Nature's Ally, similar to Palemaster minions.
Since we're going into Epic Territory at 20, and Summons are notoriously underpowered, I feel a CR:20 Summon would be fitting for a summoning class.
Maybe a Salamander, or a Lion, or an Invisible Stalker
Something that will at least survive a few hits in Epic Content.