“Freezes troops and buildings, making them uable to move or attack. Everybody chill.”
The Freeze Spell Card can be unlocked from the Arena 4 (P.E.K.K.A Playhouse).
This card can be used with Balloon, Hog Rider and some other cards to deal lots of damage to the enemy Towers. Once you deploy the Balloon/Hog/Prince, the opponent will immediately drop a card to take down your card, you can drop this Spell onto them and let your Balloon deal damage freely.
Freeze Spell can also be used to stop the enemy troops like P.E.K.K.A, which can deal a ton of damage If it reaches your Towers.