Mythos
Scenario

Easy / Standard

: -1 for each Brood of Yog-Sothoth in play.

: Reveal another token. If you fail this test, take 1 horror.

: 0. You must either remove all clue tokens from a Brood of Yog-Sothoth in play, or this token's modifier is -4 instead.

: -3. If this token is revealed during an attack or evasion attempt against a Brood of Yog-Sothoth, it immediately attacks you.

Undimensioned and Unseen #236. Undimensioned and Unseen #1.
Undimensioned and Unseen

Undimensioned and Unseen - Back

Scenario

Hard / Expert

: -2 for each Brood of Yog-Sothoth in play.

: Reveal another token. If you fail this test, take 1 horror and 1 damage.

: 0. You must either remove all clue tokens from a Brood of Yog-Sothoth in play, or this test automatically fails.

: -5. If this token is revealed during an attack or evasion attempt against a Brood of Yog-Sothoth, it immediately attacks you.

Undimensioned and Unseen
Reviews

In the case of the token, if there are currently no clue tokens on any Brood of Yog-Sothoth, one cannot choose the first option and consider the effect of the doom token done ; in this case one is compelled to choose the alternative (-4 in easy/normal, auto-fail in hard/expert).

Ruling by Matthew Newman here) :

If you are instructed that you “must” choose among multiple options, you are compelled to choose an option that has the potential to change the game state (Rules Reference, “Must,” page 16). In this case, if there are no clues on any Brood of Yog-Sothoths in play, you cannot choose that option, and must instead change the token’s modifier to –4.
manur · 2
There are only 38 cards in this encounter set, including the scenario card itself. Is the set # printed in the corner, i.e., 1/39 a typo then? — Krzysztopher · 1
Will spawn of yog attack the player when a player draws the -3/-5 symboli during an attack if it already exhausted? — Narska · 1