The presents actually take a while to do damage to troops.
There is a subtle difference between the trap and the presents, the presents are slightly smaller and the trap and the orientation of the bow is different.
It's no longer available in the current version of the game.
Defensive Strategy
Santa's Strike can be used similarly to other traps in the game.
Trivia
The Santa Strike's "present" bombs only damage units if they are standing directly on the tiles that the presents hit; otherwise no damage is dealt.
The "Unpleasant Present", a similar trap with the same appearance, was available in the 2012 winter holiday update.
The Santa Strike is the second trap with Santa instead of an auto-damage effect.
Icon Descriptions
Tapping this icon displays information about the Santa Strike, such as Damage Type and Targets.