The Conclave Add-on for Crusader Kings II has 10 achievements.
Win a war using Mercenaries.
Have someone owe you a Favor
Create a mercenary band and have them bring in money for you.
As a ruler have a council that is not content.
Successfully intervene in a youth's development to force one of your own traits onto them.
Have all members of your council be Loyalists.
Sit on the council and have every other council member as well as the ruler owing you a favor.
Have at least one child with each of the five level four education traits.
As a vassal use a favor to change a law.
Enforce peace for 6 or more vassals.