Use a Ritual Diviner for easier construction.
Activation Cost: 2,000 EV
Crystal: Weak Activation Crystal
Upkeep: 5 EV every 5 ticks
Rune Requirements:
12x Earth Ritual Stone
4x Air Ritual Stone
Total: 16 runes
The Invisible Cage
An unseen barrier of vitaemantic force encircles the ritual, preventing any creature from escaping its boundaries. Those that try are pushed inexorably back toward the center. Practitioners pass through freely, making this ideal for penning livestock or trapping hostile entities for your purposes.