A note: while your Cataclysm/Skybreach build is ingenious and I do like it, a straightforward Lightning Skybreach setup is more effective in Crucible, clearing it in 6:40 minutes with 3-4b+vb. I’d argue the set’s main fault lies in the outdated defensive profile rather than its offensive capabilities. (Not incidentally, losing the greens in the linked build will affect clearing rates more than times.)
Here I’d argue that ADCtH is a better fit for single-skill, single-mastery Iskandra (and the one mastery is Arcanist, which offers no healing at all). I’ve tested the concept, and it’s very nice.