In this modpack minecraft mobs will become more hostile, smarter and more dangerous, it also makes them able to use abilities; adds a few new biomes, structures, mobs and enviroment sounds; new mechanics for the enchanting table and new bookshelfs which gives more posibilities of getting rarer enchantments; theres also blood moons which increases the difficulty of that especific day and gives temporary buffs to all hostile mobs.
The combat system is only changed by "epic fights" mod, if you dont like using it you can turn it off; theres a new camera above the shoulder of the player for better experience; finally but not least it has "essentials" mod which gives you the possiblity of adding and inviting your friends into a singleplayer world, for a extra mention the mobs will also have a bigger vision range and every time that a move sees you there will be a warning sound that something is coming towards you.