some Cards which are important in Pve ( Missions )
Superior Optics
Tokarev Svt-40
all Sniper Cards
Unit Stays and take no Dmg( if Attack is higher then defence from enemy), so you can upgrade it.
For Destroy Missions
Captured
1 or all enemys cant attack till your next Turn.
For Survive Missions
also useful:
Spying ( disable all abilities ) when the enemy card is full upgraded.
incapcitated ( reduce Dmg by 5 or 15 )