At the bottom of the page - you'll see little Anima bubbles that start to fill up each day you resupply anima. So your first day, you only have the 1 channeled location that last 48 hours. After 24 hours, youll be able to unlock the second one that lasts 48 hours. Rinse/repeat, until .. (this is the part Im unsure about) one, or both are permanent and you get two more areas to unlock rinse/repeat. Looks like 10 bubbles (10 days) needed to fill out the bar.
I do it on my prot pally and its a breeze, although a bit slow if I dont get the right powers. I think the best offensive ones I've found are - Judgement allows Wrath to be cast Anima, then wrath has stacks anima, and then increase damage of wrath anima. I end up sawing down elites rather quickly once I have 6-9 stacks of wrath at +30-90% damage to blow through.
As far as the classes having some an imbalance - when I got to level 3 and started seeing 3-4 Elites grouped up, I knew squish dps would have an issue. I remember the same issue in Legion with "Withered Army Training" scenario. It took till early Emerald Nightmare to be out before I could get all the way through that scenario with my Shadow Priest. But my Monk I could just breeze right through the whole thing. Incredibly imbalanced in that situation - but at least with Torghast, you can grab another body to do the place with. I'm interested to see what classes will be able to solo lvl 8 before any other, though.