Here is the full list of all 19 Heavenstrike Rivals achievements.
Get a ★★★★★★ unit.
Promote a unit.
Train a unit.
Get a ★★★★ unit.
Get a ★★★★★ unit.
Complete a Daily Mission.
Complete Story Mission 21.
Reach Level 10.
Complete Story Mission 43.
Complete Story Mission 62.
Complete a Strike Mission.
Reach Level 20.
Reach Level 50.
Reach Level 100.
Be promoted to Drake Division.
Be promoted to Chimera Division.
Be promoted to Basalisk Division.
Be promoted to Archangel Division.
Be promoted to Sky Ruler Division.