You will encounter Geonach's from Lycanite Mobs every ore you mine, you will encounter every dragon in every chunk and vanilla hostile mobs are smart to basically annihilate you.
But don't worry, this modpack has 140+ mods of both medieval and tech wise to help you out and claim the world as yours.
"It's not scary, it's unsettling" - YoungSquidoo
NOTE: You need 6GB to 8GB RAM to run this for single player and multiplayer.