Here is the full list of all 29 Mighty Party achievements.
Sacrifice units 100 times
Achieve 200 rank
Achieve 1 league
Win 500 battles in PvP with Trixy
Open 5000 chests
Win 500 battles in PvP with Son of Woods
Achieve 5 league
Open 2500 chests
Achieve 100 rank
Reborn units 20 times
Reborn units 1 time
Win 500 battles in PvP with All-Father
Achieve 10 league
Achieve 50 rank
Open 500 chests
Win 1 battle in Divine Arena
Open legendary chest
Win 1 battle in Survival
Invite 10 friends
Achieve 20 league
Sacrifice units 1 time
Open 50 chests
Complete Chapter 3 in Journey
Achieve 10 rank
Invite 1 friend
Complete the tutorial
Open epic chest
Win 1 battle in PvP
Defeat first boss in Journey