The Hook Divination Card - Reward Suggestions

Make it league related. Like something that provides a league specific item. So it can 'hook' the players into the league. And as it will be "renewed" each league, this makes a reference for this rework.
Also this fits with the citation, as some seasons were a "taste" to what became "obsessions".

Or if you want to keep the "atlas relation', maybe something like an unique or super juiced map.

Last but not least, you take on the funny side and go on the word play and make it a real hook... By giving a small stack of cosmetic currencies (or lootbox).

A unique fishing rod staff weapon which has a special effect where it pulls mobs towards the player when melee attacks are made.

How about a random Timeless Jewel with "Corrupted blood cannot be inflicted on you"

Any of these, in order from my most to least favorite ideas:

Random itemized Craicic Chimeral (Imprint beast) (Singing "The hook brings you back" when you use an imprint is optional)

10x Astragali, or 10x random Expedition reroll currency

Well-rolled rare item, ilvl 86

1x Elevated Sextant

1x Eldritch Chaos Orb

Random utility flask with the enchantment "50% increased effect. -1% to this value when used"

3x Ancient Orb

Since unique watchstone were used to juice up the atlas, I like the idea of making it about the new atlas system, and make the "hook" specific league mechanics.

So maybe a map with rewarding implicits, like what the Operative Scouting Reports roll.
Or why not directly one or more Scouting Report.

A Compass with a random Sextant Mod with 16 uses.
This is sort of in-line with Unique Watchstone, as those had limited uses as well.

Maybe exclude total crap ones and make it "league specific Sextant Modifier"
this way you'll get either mirror of delirium, sacred grove, einhar, sulphite, beyond etc - you get the idea.

16-use Harvest or Mirror is really valuable. That card could be a nice find worth 10-20c.

Change to get unrelenting timeless emblem or flawless breachstone. What i mean 1/10 change to get one unrelenting timeless emblem or one flawless breachstone. You could get ether emblem or breachstone.

Doryani's Machinarium

i86 normal Jewelry with a Synthesis implicit

My suggestion would be any organ part that you otherwise only get with a "big" metamorphosis. It doesn't have to be great stuff on it, but often one thing is missing to start the event in the laboratory.

And you get other things from the respective league mechanics somewhere else too, for example: oil, incubators, clusters, etc....

only organs gets nowhere else.

I think the map optics still fit very well.

And then you could drop them primarily in maps that have something to do with laboratories or underground.