While this spell appears to be a buffed version of Fist of Yog Sothoth , it requires two hands ...with the following effect: Any Phase: Cast and exhaust to gain +X to Combat checks until the end of this combat, where X is twice the number of successes you rolled on your Spell check.

If the Investigator uses two hands for the spell, do they otherwise forfeit an attack (no hands left for weapons), take damage from the monster, and then apply the "+X to Combat checks until the end..." during the next round of combat?

Or, did I just miss something in reading this card?

No they can attack. The spell itself is effectively a two handed magical weapon. It lasts for the entire combat.

Thanks, Veet! I posted this question out on BGG, as well and received the same ratioanle...it's just like Wither or Shrivelling . That's what I get for posting so late, after a half bottle of Moscato.