Hi all,
Thank you all for suggesting Tectonic Slam. I bit the bullet and used the remaining Orb of Regrets to put points into endurance charges and changed the ascendancy node. Tectonic Slam's rework addresses all of the issues I had with other slams that I tried out: inconsistent AoE and single instance hits.
PoB: https://pastebin.com/pt8C4Uaw