Just a note - I'm fairly sure the recall psi is scaled linearly on remaining health. Sometimes the recall button displays this, sometimes it doesn't, but if I watch the psi impact it seems to always be true. (A bug afaik) As such, recalling just before death only serves to remove the short cooldown, not actually to preserve psi.
On the flip side, casting heal just before recalling a damaged boost 5 Markos actually gains psi vs. simply recalling. I think even at just 1 level of heal.
Reading more carefully, it looks like you actually mean you pull him out for that last small bit of psi when you see the incoming attack animation. Yikes, I wasn't that dedicated to micro! (I did eventually remember the trick of boosting to 4, letting him hit with lunge, then boosting to 5, though I don't know if it actually helps, especially with the Evni speed buff.) Good luck, sounds like you are on track.
Edit: TFoME is down on the 2nd (and a half) try. It can be done with Blood and Plague. Key seems to be ok with letting most stuff run till the Red/Blue junction to soften up a bit, with Wrenna (ice spear off, sleet maxed/on) on the right (point 3) and Markos on the left. Due to the amount of jumping and incoming damage, Furious Start is probably stronger, but the plague setup might be a little more forgiving since some of your damage is passive.
If you try the plague route on this one, make sure to run the first dragonfire 2-3 before the end of the RGB darks - the cycle is slightly shorter than the dragonfire cooldown, and you want the timing to be good later on. Also, due to the later setup point, use fury right at the start, you'll have it back in time. Sometimes had to jump Niru and Slak back onto the throat though - roar + whirlwind => really good meat-grinder.
Somewhat crazily, I forgot to swap to Beast Weapon+ for Wrenna, had the chill one instead. More raw damage, but 3x against worms is huge, so I bet that'd make it easier. Guess it proves you can get this even if you didn't upgrade the Beast Weapon yet. Did retune my Wrenna after looking more at the cast delays, that did matter a surprising amount.