Maxine Newman's clarification on the effects of the tokens:

This is a bit of a tricky situation so I will outline it step by step, as best I can. =)

Rex’s Curse triggers during Step 6, when you determine success/failure of the skill test. By that time, some chaos token effects will have already triggered. Chaos token effects that say “if you succeed" or "if you fail” will not have triggered yet, as Rex’s Curse interrupts the timing of those effects, but since Rex’s Curse does not cancel or ignore the token (like Wendy’s Amulet or Grotesque Statue does), the token will have created a delayed effect that will trigger during Step 7, regardless of whether the token is returned to the bag or not. Chaos token effects that simply have an effect (like “Place 1 doom on the nearest Cultist enemy,” for example) trigger during Step 4, before Rex’s Curse triggers.

After you return the chaos token and draw a new chaos token from Rex’s Curse, the sequence returns to Step 3, and you should follow the sequence in order as normal.

So, in your example:

• You draw the cultist token during step 3. During step 4, you place 1 doom on the nearest cultist, as part of the token’s effect.
• When you would pass the test (during step 6), you return the revealed chaos token to the bag and reveal a new chaos token. This returns you to step 3 of the sequence.
• You draw another cultist token! Poor Rex. During step 4, you place another doom on the nearest cultist.
• Step 6 rolls around again and you pass the test, so Rex’s Curse remains in play.

Had you revealed a chaos token that says “If you succeed / if you fail” during your first reveal, it might go like this:

• You draw the hypothetical token during step 3. It says “if you fail, take 1 horror.” This creates a delayed effect that will deal you 1 horror during step 7 if you fail the test.
• When you would pass the test (during step 6), you return the revealed chaos token to the bag and reveal a new chaos token. This returns you to step 3 of the sequence.
• You draw another hypothetical token. This creates another delayed effect that will deal you 1 horror during step 7 if you fail.
• If you failed this hypothetical test, during step 7, you would take 2 horror (one from each of the tokens).

I hope this clears things up. Cheers!

1.

With de Vermis you relive your past,

And Alyssa's got next turn's forecast,

But both, you'll allow,

Drop a deuce on your 'now.'

Let the moon clear the crap you've amassed!

2.

The debt on that Pact that you made

Has come due, and it needs to be paid.

You’ll dry up like a prune—

But wait there’s the moon!

Kneel, sinner, and pray for its aid.

3.

Twice now damnation you’ve dared,

And twice has your black soul been spared.

But now you and Dave

Are ripe for the grave.

For three pardons no deck is prepared.

If you are wondering how strong this card is, just imagine that it says for no resources and no actions, an investigator at your location draws 10% of their deck. Yeah, I'd say that is pretty good.

Currently, only 6 investigators can take this (every Seeker except Norman). Among them, the hardest thing about taking Cryptic Research is choosing to prioritize this. 4XP is a lot of XP to spend on a card and Seekers have a lot of places they could be spending their XP. Add to that the fact that Seekers have a lot of card draw even with no XP at all. It's truly not hard to draw through your entire deck with Seeker, even with no XP at all. If you are worried about redundancy, then think of it this way: Cryptic Research could help you consolidate some card drawing power into one card, leaving you more space to add other effects.

However, don't neglect the multiplayer possibilities. There are other factions that have a hell of a time drawing cards, Guardians in particular. If you are doing a classic Seeker + Guardian multiplayer campaign, this can help your Guardian draw through their deck to get cards they need, while you draw through your own deck with your own tools.

As other reviewers have noted, this card pairs beautifully with Alyssa Graham. Basically, Alyssa lets you look at the top encounter card for free, but makes you pay a hefty price -- doom -- to get rid of it. Split the Angle makes you pay to peek -- an action -- but then discard what you saw mostly for free. Put the two together, and it's ALL free.

Commenters, however, have done what commenters do, and raised annoyingly rational objections. They point out that you only get one StA, so you might never find it at all, and if you do, there's no guarantee Alyssa is in play, etc. etc., doom and gloom. Unfortunately, they are right...

I think, in the end, StA takes a sweeping deckbuilding commitment to make it reliably good. Step one is including 2 copies of Alyssa Graham. As others have noted, you'll probably want to upgrade into level 3 Scrying. Scrying is especially handy in solo, because it gives you multiples turns of information about the encounter deck in a single use. Say you're solo-ing away, and in the tea leaves you find a pair of ancient evils and something relatively harmless. You can arrange them into an Evils-Meh-Evils sandwich; and use StA two turns in a row to discard the two slices of death-bread, drawing only the mild Meh in between (and something random) -- all for no actions at all. Of course, the downside here is that you are now using both your arcane slots on encounter-deck mining...

As long as you're investing in all these cards that let you burn through or optimally order the encounter deck, you may as well toss in Stargazing (you are an astronomer, after all...). You're much more likely to actually draw the The Stars Are Right if you can dig for it with Alyssa/StA/Scrying.

With 2 copies of Alyssa and 2 copies of level 3 Scrying, the odds are now pretty good that if you do manage to draw StA, you'll have something to pair it with. If you are absolutely determined to make this combination happen, Word of Command can help you find StA or Scrying, and Calling in Favors can help you track down a shy Alyssa.

By now, we're talking about quite a commitment! Is it worth it? Strategically, maybe not, but it might make for a fun thematic build. A prescient astronomer with occult leanings reading doom in the night skies -- and then somehow averting it by means of dubious geometry or an eldritch astrolabe -- that sounds pretty Arkham-y to me.

While Practice Makes Perfect has some good uses with combatants, I also wanted to point out that Mandy Thompson can use it to rather ludicrous effect. Using it on an arbitrary investigate can turn it into a single trigger where you can pick two of the most fitting cards to use out of a selection of cards including Deduction/Deduction (2) and Perception. This can turn a single card into both a boost and bonus clues or card draws over multiple tests. It only gets better depending on the secondary class picked - you can also branch into things like Enraptured with mystic access, or Momentum or Three Aces with rogue access.

The ability to improve Practice Makes Perfect from one draw/boost/bonus effect into two draws/boosts/bonus effects is immense, and given the symbols on many of those cards, it means she can throw it on pretty much any investigate action to get a lot of effective resources on top of a notable boost.