A few things about the Crimson Bat (and I do realize that a lot of this entry is from earlier write-ups, but I seriously think they should be revisited):
1. 90-meter wingspan, 20 meters nose to tail, 1K metric tons... size 180? That’s like saying a football field is only as big as one of the teams.
2. I just want to make sure— the magic/spirit absorption effect of the Glowspot means no one not a Priest or Rune Lord of the Bat has any spirit magic within 4-20 km of the Bat? (And how is that range determined?) All random spirits in the area are absorbed? That can alter a campaign instantly, conflicting with encounters for hundreds of miles in every direction.
I am beginning to think that even your stern warnings might not be enough. Given how much the Bat can completely screw up the magic over the entire region, maybe its approach should be treated as a historic event, on a par with the eruptions of Pompeii and Karakatoa, not merely a hazardous one. As wrtten, a visit from the Bat is like the drop of a neutron bomb. Depending on how long the Bat stcks around or how often it returns, the very ecology in an area could change, and whole cities — even Lunar-friendly ones — could have their commerce and magic disrupted for years, or permanently.
(I had the Bat in one campaign, once, and I had the Glowspot as about a mile radius below it. I also decided that spirit magic, rather than being negated, cost double POW to cast, and a special failure meant the POW was absorbed. (A critical failure meant that all the caster’s POW was absorbed, and they fell unconscious.) This was basically so players didn’t feel absolutely helpless in the face of the Bat. They couldn’t hope to fight it, but they could still fight its entourage.)
3. Even given the size of the Bat, I think the ticks it carries are too large and too numerous. Rather than thousands of SIZ 1D4 ticks, hundreds of SIZ 1 (maybe the size of a man’s hand) seems like plenty to me. (I’d also reduce their bite damage to 1D4 or 1D6.)
4. Given that its effect is the same as the Demoralize spell, is there any way to resist the effects of Chaos Scream?
5. Can the Eye Spit be dodged or parried? Can any armor or creature’s hide block it, even partially?
6. The chart for the Bat’s attacks says “see below” for the effects of Eye Spit and Chaos Scream, which are listed two pages earlier. Perhaps that chart was originally closer to the beginning of the description...?
Sorry if I’m getting too philosophical and/or pedantic. I just want to help make this the best it can be!