Hello and thank you for the great game devs,
-Double the effects of potions.
-Drop rate is increased by 100%
-Range of all towers is decreasd by an x amount.
Tower Cards :
Dark: Grave Digger (epic)
All towers in range will grant double amount the gold if sold.
For each tower destroyed Grave Digger will get 10% XP and 10% damage.
Nature: Big Foot (epic)
Active: causes an earth quake, slowing all units in the map by 50%
Santa Claus sounds really specific, but could be really cool for that specific playstyle!