From Rampage Knights Wiki
How to beat the challengeFrost orb to freeze enemies. Frostblade has a chance to freeze on attack, and Icicle will freeze all enemies in the room when a player gets a kill. Hailstorm also has a chance to freeze on attack, and has a chance to drop ice axes from the sky which freeze enemies.
The Scroll of Freeze can be used to free all enemies in a room, and such is best used in a room with lots of opponents.
Freeze time x2.