The solo leveling limit conjecture

Two possible major categories I don't see mentioned yet:

* Full End refill from Domination. Back when Dom gave a damage bonus, people had (pricey!) builds with "perma-Dom" fairly early on, which implies enough recharge to fire Domination more often than every 90 seconds; and there were characters with double-stacked Dom, which unless I'm mistaken means <45 sec recharge.

* Confuse. This is sort of a special case of pet endurance instead of your own, with the additional bonus that there's a continuous supply of End with every new foe. The non-linearity of the damage to XP works in your favor if you juggle it right; the oft-quoted "do at least half the damage, get at least 80% of the exp" point may not be the optimum, but points out the possibilities.

Plant Control gets Seeds of Confusion at level 8; you could have Seeds, Flares, Incenerate, and Fire Breath exemped all the way down to level 3 under the current system, which has some weird potential given the ultra-low-level concept listed previously. Picking Natural or Mutation and having someone mail you damage Yin-Os would allow you to be pretty alarming even at real levels not much over that.

Anecdotally, my Plant Control / Fiery Assault Dominator did not need Stamina before the Dominator changes, and I was not particularly building for it and only to the mid-20s. With the Seeds of Confusion a core part of her attack style, the addition of Consume and planned for eventually picking up Power Sink (and possibly Surge of Power, using Domination to counter the crash), and having a variety of AoEs and pets (Carrion Creepers, Fly Trap, possibly Mu Guardian), I'm pretty sure End wasn't the limiter. Oh, and Fiery Embrace may be helping as well. Post-Dom update, I did respec her to have the Fitness pool, as her attack chain sped up; but IIRC post-update-post-respec I can't recall her running out of End even with Hasten running.

The interesting question is whether with a targeted build the enemy-killing rate could be cranked up on a uber-pricy build variant of the above to be noticeably above the limits you start with here; I'm not someone who plays at those sorts of rarefied levels enough to have a good feel for it, but I suspect that in a sufficiently idealized setting it could be done.

Side notes and musing: if she "went blue" and took Fire Mastery instead, would she get Consume twice? Better or worse than Power Sink? Or go Soul and get Dark Consumption, Soul Drain, possibly Fortunata? She got sidelined before epics for largely social reasons (i.e. unrelated to build), and I've not looked at her in a while. Certainly plenty of End-management tools available, to the point that I'm pretty sure that in the upper levels the limit would be on the damage output per time rather than being End-limited. (Over half of your chart's total time to 50 is spent post-41, with potentially the first epic power picked.)

APPs are available to all level 41+ characters, regardless of alignment. You wouldn't need to "go blue" to get Fire Mastery. I don't have a high-level dom, but according to Mids', Dominator Fire Mastery has Rain of Fire, Fire Ball, Fire Shield, Rise of the Phoenix, and Melt Armor, so you wouldn't be able to get Consume twice. If you're using it solely for endurance, I'd say that Power Sink is better than Consume if you could only pick one - Power Sink is a base 25%/target instead of 20%, and it's autohit where Consume needs an attack roll. Dark Consumption has the same 25%/target as Power Sink, but it also requires an attack roll. Soul Drain would be more help (in my opinion) to non-plant dominators. Plant sees a fair amount of its damage come from pets and confuse, neither of which is boosted by your personal damage buffs. From the three epics you listed, I probably would choose the Mu Mastery to go with a Plant/Fire.