Updated!
Some of the 'mancers have been adjusted - minions will no longer animate their own severed body parts. Keuranomancers have been nerfed - each lightning man can only stunlock one target at a time and only at touch range, so outnumbering them or using projectiles will work. Hydromancers are a little less of a joke, they and their minions can now suffocate enemies.
The Bloodgod mod has been included, although there is no way to actually summon it unless you manually add [PERMITTED_REACTION:DRINK_BLOODGOD] to the dwarven entity raws. The Avatar of the Blood God is a stupidly powerful creature (a humanoid made of slade with adamantine teeth, nails, and beard, and magma for blood) that is hostile to everything. so you must lock up the dwarf that drinks the draught before their transformation is complete. If you keep it in your fort, it will grant combat bonuses to all your dwarves, BUT only if you sacrifice a creature to it every month or so. Go too long without a sacrifice, and half of your fort will go berserk and try to kill the other half. And even with the occasional sacrifice, sometimes it will create hidden fun like vampires or necromancers. Also, if you try and get out of it by killing it in a cave-in, your fort will also go berserk - once you've summoned it, you're stuck (though some migrants might survive if they haven't been made thralls yet). It...isn't really worth the bonuses, but is meant as an extra challenge.
Besides that, there's some new creatures:
Strigoi (a flying vampire species)
Naga (a little different from Masterwork's Naga so Meph might want to remove them)
Witches (they will give a random month-long curse to their enemies, but will grant boons to their allies - if you can get one to join you, you're in luck)
Kapre (tropical tree trolls)
Mogui (fluffy pets that breed explosively, but can only mate when they are in the rain - which also makes them go berserk and attack all non-mogui. I should probably come up with a reason why you would want to go through the trouble of breeding them.)
Carbuncle (extremely rare pets that grant protective effects to their owners - or you can butcher them for their ultra-valuable gemstone)
Baku (tapir-sized pets that eat the negative energy of the creatures around them, producing good thoughts - but if left unfed for too long, they might suck out a creature's emotions. Also be careful of their milk, it's made of concentrated nightmares...though it does give a creativity boost.)
Squonk (constantly crying, and when they get sad enough they melt)
Drop Bear (vicious ambush predator koalas)
And a new semimegabeast, Ammit, hippo/lion/crocodile hybrids that eat souls - anyone bitten by one (that survives) loses the ability to learn and speak permanently.