Okay, hopefully Kevin will see and answer this one. Here's the problem: it says on the Herald sheet that "when Cthulhu awakens, add up the total toughness of any monsters with the plus dimensional symbol in play. The investigatos must inflict that many additional successes on Cthulhu in order to defeat him."
Now, do you have to inflict those successes BEFORE you start taking Doom tokens off, AFTER you've taken the last Doom token off, or can you choose? Why is this question even important? Because Cthulhu regenerates one Doom token a turn, but he presumably does NOT regenerate the extra successes needed from plus dimensional symbol monsters. So let's say that both Star Spawn are out when Squid-face awakens, and on the first turn the Investigators score six successes against Cthulhu. If you have to take off all the Doom tokens before taking off the monster toughness, then four of those successes will be lost. If, on the other hand, you can take off the monster successes first, then you can take off both Star Spawn and there are no Doom tokens removed for Cthulhu to regenerate, enabling you to laugh and make rude gestures at him (You might as well, he'll almost certainly kill you before the end of the fight anyway).
What's the ruling, Kevin?