Here is some add copy found on a web store that offers preorders. It looks like it is old from when Monsters II was one book not split into two books one glorantha the other book more generic monsters. It gives some hints at what might be in both books, however things could have changed here it is:
The second in the series, Monsters II is a large collection of creatures and species for use in the collective RuneQuest gaming settings. It is the continuation of the work began with the first Monsters title – but bigger, fuller and even more crowded with interesting and unique creatures from every corner of the imagination.
Returning dozens of Gloranthan beasts and races back to RuneQuest, Monsters II gives Games Masters and reader’s use of many of the old favorites. With the return of the Choram, Jelmre and even the Waknath, Gloranthan campaigns can fill in many of the corners that our first Monsters collection left empty. There are also dozens more newcomers as well that could be found in Glorantha as well as other gaming settings that use the RuneQuest system.
Monsters II is filled from cover to cover with a host of different beasts and creatures that could make good encounters and player characters. From the old mythological traditions like chimera and hydras, to unique races like the semi-vampiric sanguines and spirit wolves, this book contains a multitude of wonders and horrors to unleash upon the RuneQuest game worlds.