My bad, phone copy and paste.The Fighter Rune Knight is actually up to 24 now. Fixing:
Artificer Armorer 9
Cleric Order Domain 19
Cleric Twilight Domain 6
Druid Circle of Stars 20
Druid Circle of Wildfire 19
Fighter Rune Knight 24
Paladin Oath of the Watchers 9
Ranger Fey Wanderer 19
Warlock The Genie 14
No problem, you weren't the only one tomiss a response. I just didn't want it lost.My bad, phone copy and paste.
Long or short, for the runes. Prof bonus times, for giant. It has something of an nova-focus - like you say - but it's a hell of a nova. I feel like the archetype would play out more successfully if those runes were slightly less strong, but usable more often. Restrained + 2d6 damage a turn for a minute, strength save to break!
I guess the design is aiming to offer something exciting, but I just wish the runes were better balanced... including across the runes themselves.