A special place where Cactus Cathy (overlaid) grows her own cacti. The card's info says:
LAIC-EN038:
Cactus Sanctuary
Field Spell
The ATK and DEF of each face-up WATER monster becomes 0, also their effects are negated. During either player's turn, you can draw 1 card for each face-up WATER monster whose ATK and DEF are 0 by this effect. You must control "My Pudgyville Pony Cactus Cathy" to activate and to resolve this effect.
Common