This deck is very similar to my old Masked Siraf list already posted in this site. New cards made new things possible, adding way more reliability to the archetype. Some considerations on the new cards:
Vara, Vengeance-Seeker: As good as everyone was expecting, she works incredibly well in green mask, since she has the innate lifesteal to pump mask and deals with aegis, making a deck that already had little issues removing aegis due to the devour + end of the story combination struggle even less.
Azindel, Revealed: Great late game threat to deploy after you harsh rule and dark return, makes the deck's threat variety even broader with the option to dark return either him or Siraf if they don't win the game the first try.
Cute card of the deck:
Dead or Alive: This turned out to be a random test include that actually surprised me quite a bit, green mask is one of the few decks that have the life total to support taking a bunch of hits, and the blowout caused by harsh ruling a wide board is made even more absurd by reloading your hand (and possibly even overdrawing). While it can obviously be dead in plenty of situations, I feel like at 1 it does its job and isn't too harmful to the deck's overall game plan if it isn't useable against the particular deck you are up against.
Cards to consider:
Annihilate: Extremely strong right now, maybe even more so than
Slay, but I feel like there are some multifaction unit decks that could cause some trouble to the deck more than hitting those midrange decks even harder than we already do in a justice control deck.
Stronghold's Visage: Very strong in the right meta, creates an innate clock with mask and gives temporal control a run for its money if you manage to get enough of them up fast enough. If temporal control ever becomes as popular as it used to be last week (and it probably once the novelty of the new campaign wears off) you should definitely add a number of them into the deck.
Feel free to mess with the removal suite, the only fundamental cards are the harsh rules.