The Foul Beasts Mod includes these things:
The Amiun, which you can tame with a diamond block and he follows you around.
The Octomaloid, a freaky spider-like creature.
The Iron Harpy, which flies above you and swoops down to kill you.
The Vine Mage, a odd but dangerous woody creature.
The Mortinebine. This is probably the second most dangerous creature, resembling a eerie tornado monster.\
The Hydrodinomorph, a new common but deadly sea monster.
The Nocparietile, a cave monster that will block tunnels.
Peloric Ivy, which does damage when you touch it.
Totem Of The Water Guard, which spawns 3 Marantimaluses
Totem Of The Majiks, which gives you invisibility and fire protection when in hand, and sets enemies alight when you hit them.
The Twister Bow, which is obtained by killing the Mortinebine.
Finally, The Photovore, the most powerful mob in Minecraft. He will come to haunt you.