The spell Is "Open the Third Eye" which allows you to take the "Third Eye" special card. The special card gives you the afore mentioned modifiers +1 Maximum Sanity, -2 Maximum Stamina, and +2 to horror checks (not +3). It does not affect your current Sanity or Stamina scores, unless your current Stamina is now in excess of your maximum; in which case you lower your current Stamina to your new maximum Stamina. One additional effect is that as long as you have the "Third Eye" special card, you may not be Cursed (although, if you are already Cursed, this card does not change that).
This spell is intended for long term use, as its short term benefits are fairly minimal. Fortunately, you do not have to cast this spell every round. You can keep the "Third Eye" special card as long as "Open the Third Eye" remains exhausted; and you may opt not to refresh "Open the Third Eye" during upkeep. This spell is ideal for non-spellcasting characters, as they can raise their Lore to 3, and attempt the spell each round until success. With a +0 Casting Modifer, that should not be more than a few rounds; and at a Sanity Cost of 0, they do not suffer for failure. Once they succeed, they adjust their Sanity and Stamina accordingly (such as turning a Sanity 3 / Stamina 7 character into a more balanced Sanity 4 / Stamina 5 character). Lastly, adjust your skill sliders to their optimum positions. For a non-spellcaster, drop your Lore to 0, as you will not need to cast this spell a second time, unless you choose to cancel its effects. Also, with the +2 bonus to horror check, you can move your Fight / Will slider a little more in favor of fight. Don't forget, as an added bonus, you will not have to worry about being Cursed any longer!
I suppose you can tell from my above review, I like this spell!