I can’t post a log because I play on iPhone, but here’s a walkthrough. Could be better plays, but this gets you through the mission. The first spoiler is helpful clues to try on your own. The second one is my full walkthrough.
Summary
Except for Writhe’s first two turns, you ignore the manifestations. Writhe’s first two turns are used to play Swallowed by Shadows. After that, let Infinitor destroy the most damaging ones. (Recalescent Hellion, usually) Erratic Form lets you destroy the cloak for good effects, cycle through your deck, and and keep a lot of cards in hand for damage reduction.
Stuntman needs to get The Usual Solution to get rid of Battalion Command Center. Otherwise the environment will get a lot of cards out that make life rough. Use Training Montage to to get to that card. After that, do as much damage as you can to Infinitor before you he goes down.
Mainstay plays Dura-Steel Studded Vest then Shard Strength and then pretty much whatever he wants. If you discard equipment, Drop the Hammer becomes very powerful later on.
Summary
Turn 1:
Put the Crushing Cage on Mainstay.
Stuntman plays Training Montage (pick up the extra cards) and then Dramatic Cliffhanger. Uses his power to hit Infinitor.
Writhe plays Swallowed by Shadow and destroys Crushing Cage then gets his Shadow Cloak.
Mainstay plays Durasteel-Studded Vest then uses the vest’s power. Discard a second vest and Sweet Rhonda.
During environment phase, destroy Dramatic Cliffhanger. Play Training Montage (again taking damage for extra draws) then play No Time to Bleed and ping Infinitor.
Infinitor @ 61
Turn 2:
Destroy a Lambent Reaper. Destroy No Time to Bleed and hit Infinitor. Writhe discards Portable Dark Lab to save some health.
Stuntman plays the Usual Solution, hitting Infinitor and destroying Battalion Command Center.
Writhe plays Swallowed by Shadow, destroying both Recalescent Hellions then gets his cloak back.
Mainstay plays Shard Strength and then pings Infinitor.
Infinitor @ 45
Turn 3:
Destroy Recalescent Hellion. Writhe discards Unnerving Target to avoid damage.
Stuntman plays L’Embuscade then pings Infinitor.
Writhe plays Erratic Form then skips power phase. Discard second Erratic Form at end of turn.
Mainstay plays Preemptive Feedback then pings Infinitor.
During environment, Stuntman destroys L’Embuscade to hit Infinitor. We let the Black Hole Generator out instead of discarding. Writhe does not discard.
Infinitor @35
Turn 4:
Destroy Twisted Miscreation. Discard Nowhere to Hide for damage avoidance. Do not destroy Preemptive Feedback. Stuntman goes down.
Stuntman has Mainstay play Mano a Mano on Infinitor.
Writhe plays Nowhere to Hide and skips power phase.
Mainstay plays Bad to the Bone then hits Infinitor a bunch, including destroying Preemptive feedback at end of turn.
Destroy Blade Battalion Platoon.
Infinitor at 8
Turn 5:
Destroy Lambent Reaper.
Writhe has Mainstay play Drop the Hammer, destroying Durasteel-Studded Vest and then playing another Drop the Hammer and Infinitor goes down.