Here is the full list of all 20 Terminal squad: Sentinel achievements.
Complete level 300.
Complete level 200.
Collect 100 000 000 credits.
Deal 100 000 damage.
Complete level 100.
Complete 50 tasks.
Kill 10 000 enemies.
Complete level 50.
Complete 20 tasks.
Collect 100 000 credits.
Complete 10 tasks
Kill 1000 enemies.
Spend 120 minutes in battle.
Spend 60 minutes in battle.
Spend 30 minutes in battle.
Deal 1000 damage.
Kill 100 enemies.
Collect 1000 credits.
Complete level 10.
Deal 100 000 000 damage.