Anyone know a Good Plugin?

I am creating a server..
The kind of server it will be is like kind of a Vanilla, with a few plugings.

So, basically a survival, with a few extra stuff.

There will be custom bosses in certain areas, custom achievements.

But we need some more things.
I'd like a plugin where you can config something to make it custom, like the achievements and bosses.
Although, I'll be making the bosses myself..

Is there anything out there that'd be good?
Please comment a plugin, thanks..